Composite scaffold for the repair, reconstruction, and regeneration of soft tissues

ABSTRACT

A composite scaffold having a highly porous interior with increased surface area and void volume is surrounded by a flexible support structure that substantially maintains its three-dimensional shape under tension and provides mechanical reinforcement during repair or reconstruction of soft tissue while simultaneously facilitating regeneration of functional tissue.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/802,391, filed Feb. 7, 2019 and U.S. Provisional Application No.62/970,620, filed Feb. 5, 2020, the entire contents of which areincorporated herein by this reference for all purposes.

Further, the entire contents of the following applications, filed by thesame applicant on an even date herewith, are incorporated herein by thisreference for all purposes:

U.S. patent application Ser. No. 16/785,490, filed on Feb. 7, 2020,entitled “COMPOSITE SCAFFOLD FOR THE REPAIR, RECONSTRUCTION, ANDREGENERATION OF SOFT TISSUES;”

U.S. patent application Ser. No. 16/785,512, filed on Feb. 7, 2020,entitled “COMPOSITE SCAFFOLD FOR THE REPAIR, RECONSTRUCTION, ANDREGENERATION OF SOFT TISSUES;”

U.S. patent application Ser. No. 16/785,524, filed on Feb. 7, 2020,entitled “COMPOSITE SCAFFOLD FOR THE REPAIR, RECONSTRUCTION, ANDREGENERATION OF SOFT TISSUES;”

U.S. patent application Ser. No. 16/785,529, filed on Feb. 7, 2020,entitled “COMPOSITE SCAFFOLD FOR THE REPAIR, RECONSTRUCTION, ANDREGENERATION OF SOFT TISSUES.”

FIELD OF THE INVENTION

The disclosure relates to soft tissue repair and reconstruction, and,more specifically, to a composite scaffold useful for stabilizing softtissue injuries or defects while facilitating the regeneration of newtissue.

BACKGROUND OF THE INVENTION

Biologic and synthetic scaffolds for use in tissue engineeringapplications and surgical repairs and reconstructions are known,however, few are capable of providing the optimal combination of asufficient: porosity for cellular ingrowth, biologic matrix and surfacearea for cell migration and proliferation, interconnected void volumeand dimensions for meaningful extracellular matrix deposition and tissueregeneration, composite mechanical properties and mechanical loadsharing with local tissues to encourage functional tissue maturationwhile resisting collapse or compression under said mechanical loading,and bio-resorption timeline which supports the tissue repair throughcomplete healing while facilitating the regeneration of functionaltissue.

Some scaffolds, such as hernia mesh have sufficient mechanicalproperties to complete a surgical repair, but lack the behavioralcharacteristics which are not optimally suited for healing andregeneration of soft tissues of the knee, ankle, shoulder elbow andhand, and non-musculoskeletal soft tissue. Many such scaffolds are madeof permanent synthetic polymers which can elicit acute or chronicadverse inflammation, pain, or complications. In addition, manymesh-like scaffolds are essentially two-dimensional with insufficientsurface area for cell ingrowth and insufficient void volume for bulktissue regeneration, and, therefore are not conducive to regeneratingfunctional tissue. Conversely, most biologic scaffolds for the repairand reconstruction of soft tissues are derived from bulk tissuesharvested and processed from either allogenous or xenogeneous sources,and often have slow or incomplete healing due to any combination of bulkarchitecture, tissue source, and processing method. Highly processedbiologic materials that are reconstructed into entirely newarchitectures, such as collagen gels or sponges, can be produced withsuitable porosity for tissue ingrowth but lacking suitable strength andresistance to collapse for use for ligament or tendon repair.

Many of the commercially available scaffolds composed of fibers haveappropriate mechanical properties but are inadequate for functionaltissue regeneration due to shortcomings of the architecture derived fromexisting manufacturing processes such as knitting, weaving, braiding,and non-woven methods such electrospinning, pneumatic-spinning,melt-blowing etc.; this is because the fibers have insufficient spacebetween filaments and/or fiber bundles (inadequate porosity or voidvolume or density—e.g. typical of electrospun textiles), or too littlesurface area, void volume and dimensions for meaningful tissueregeneration (e.g. typical planar warp knit textiles or braids, or fiberbundles), or when adequate void volumes are created, it is either notcontiguous on a cellular and biologically-relevant scale, or itcollapses as the structure is tensioned.

Accordingly, a need exists for a scaffold and method of repairing orregenerating ligament tissue.

Another need exists for a scaffold which is composite, i.e. mimics themechanical properties of native tendons and ligaments.

A further need exists for a scaffold which provides adequate porosityand interconnected void volume for cellular infiltration and tissueingrowth, while substantially maintaining its shape under loading ortension.

A still further need exists for a scaffold which is bio-absorbable overa period of time which supports healing for a number of weeks or monthswhile facilitating the regeneration of functional tissue capable ofbearing mechanical load following scaffold resorption.

Another need exists for a scaffold which minimizes synthetic polymerdensity and maximizes the surface area to volume ratio of the scaffold,thereby limiting the foreign body response and improving tissueregeneration.

Yet another need exists for a scaffold which has an adjustable length,width, and height for different procedures.

Another need exists for which a bioresorbable scaffold regeneratestissue of sufficient strength and thickness following completeresorption of scaffold material.

Yet another need exists for a scaffold which provides a secondarysupport matrix capable of encouraging cell growth spaced apart from thescaffold to encourage tendon or ligament tissue ingrowth.

Still another need exists for this scaffold to have engineered regionsof variable dimensions, density, porosity, material composition, fibertype, and surface characteristics to improve the tissue regeneration andor surgical handling and implantation.

SUMMARY OF THE INVENTION

Disclosed is a composite scaffold for ligament or tendon repair thatprovides mechanical reinforcement for the repaired and healing tendon orligament. In embodiments, the composite scaffold comprises a supportstructure which defines a void volume. A porous material or hydrogel isdisposed within a void volume of the support structure. The supportstructure reinforces and supports the porous material/hydrogel, enhancethe tensile strength of the scaffold and resists compression as thescaffold is extended or subject to elongation forces. The porousmaterial/hydrogel has a porosity and void volume that allows adequateextracellular matrix deposition and new functional tissue regeneration.In embodiments, the void volume is contiguous or essentially contiguousalong the long axis of the scaffold, which allows cells to fully migratewithin the device and for new tissue to form with an orientation in theaxial direction of the scaffold, while being protected from significantcollapse, compression or excessive dilation during mechanical loading ortensioning of the scaffold. Optionally, all or part of the scaffold maybe hydrated with biologic fluids such as blood, bone marrow aspirate,platelet rich plasma, autologous or allogeneic cells to modulate ordirect the immune response and further facilitate and accelerate healingand tissue regeneration.

The disclosed composite scaffold possesses a large surface area forcellular proliferation and migration, but also a sufficiently large,interconnected void space to allow tissue ingrowth, extracellular matrixdeposition, and biomechanical remodeling into functional tissue.Further, the scaffold possesses the ability to maintain a highly porousstructure under tension, e.g. resisting collapse, during a surgicalprocedure and following implantation thereby maintaining the ability forcell infiltration and new tissue ingrowth throughout the entire scaffoldunder physiological loadings. These loadings are mechanically sharedbetween the device and local tissue due to the composite mechanicalproperties of the device, i.e., prevents stress shielding of proximal,repaired, or native tissues, as well as the developing neotissue withinthe scaffold itself. Further, these composite mechanical propertiesencourage the mechanobiological signaling of cells within the scaffoldto differentiate and form load-bearing, oriented extracellular matrixand connective tissues. The disclosed composite scaffold can bemanufactured using various different textile and composite manufacturingmethods, and is not limited to a singular manufacturing technology.

The disclosed composite scaffold provides a highly porous and flexiblestructure that substantially maintains its three-dimensional shape undertension and provides mechanical reinforcement of the repair orreconstruction-first via scaffold mechanical properties, andsubsequently, through newly regenerated functional tissue as thescaffold is resorbed.

The disclosed scaffold may have distinct regions with differentmechanical properties to facilitate fixation or differential tissueregeneration. In embodiments, the composite scaffold may be impregnatedwith cells, biologic aspirates or bio-active agents prior toimplantation to create a biological “band-aid”. In other embodiments,the bio-inductive scaffold is seeded with auto-, allo-, or xeno-genousderived cells for a temporary pre-culture period to allow the cells toelaborate a collagen-rich extracellular matrix within the scaffold. Thescaffold may then be processed and/or decellularized to leave afiber-reinforced tissue scaffold that can be subsequently implanted, ormay be implanted “as is”. The disclosed scaffold may be compatible witha variety of currently available fixation methods, e.g. suture, sutureanchors, tacks, staples, etc.

The disclosed composite scaffold provides a mechanism to space tissuefibers apart from each other within the scaffold to provide room foringrowth for higher quality tissue not disrupted by polymer or thecorresponding inflammation. The microporous matrix acts as a stabilizerthat helps to maintain such space and allows for a larger surface forcells to grow so tissue can mature while the primary fiber of thescaffold still retains strength. If the microporous matrix resorbs at afaster rate than the support structure, a complete mass loss of themicroporous matrix can occur so that tissue can reclaim and remodelwithin the newly created volume in vivo, while the primary supportstructure retains strength, allowing cells to first invade andencapsulate the structure but also create functional tissue over time.Additionally, if a natural material is used to create the secondarymatrix, such as collagen, a reduction in scaffold inflammation mayresult and further encourage cell ingrowth into the scaffold while notin contact with any of the synthetic fibers comprising the supportstructure.

According to one aspect of the disclosure, a composite scaffoldcomprises a first matrix and an optional second matrix which may beintegrally formed with one another to maximize the surface area tovolume ratio of the scaffold while still maintaining mechanical andstructural integrity. According to embodiments, the first matrix may beimplemented with the three-dimensional textile structure comprisingfirst and a second support layers spaced apart to define an interiorspace or void therebetween. Multiple spacer elements extend between thefirst and second support layers to maintain the support layers separate.The first and second support layers may have different geometries,fibers, or material compositions. The first and second support layersand spacer elements may be implemented as a three dimensional textilecomprising multi-layer knitted or woven surfaces of multifilament fibersor monofilament fibers, or any combination thereof, formed of anycombination of synthetic bioresorbable polymers, natural polymers and/oradditives. The second matrix is disposed within the void space betweenand proximate the first and second support layers of the first supportmatrix. The second matrix may be implemented with a low-density, highsurface area material comprising any of a sponge, foam, felt, texturedfibers or yarns, collagen or tissue-derived material, or any combinationthereof. The first and second matrices of the composite scaffold mayhave the same or different structure, composition, and bioabsorbablecharacteristics to facilitate optimal regeneration of functional tissue.

In one embodiment, the composite scaffold may have a minimum thicknessof approximately greater than or equal to 1 mm. The thickness of thescaffold may be uniform along a length thereof or may vary in arepeating or non-repeating manner, depending on the particularapplication for which the scaffold will be utilized. In otherembodiments, the disclosed composite scaffold may have length dimensionsbetween approximately 2 to 1000 mm, depending on the particularapplication for which the scaffold will be utilized. The disclosedscaffolds may be manufactured in different incremental lengths or may bemanufactured in lengths which may be cut or customized by practitioneras desired or as appropriate for a specific procedure.

According to one aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space; and a structure supporting themicroporous matrix; wherein a surface area of the composite scaffold isbetween approximately 0.6 m²/gram and 1.2 m²/gram.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space having a measurable volume; and astructure supporting the microporous matrix; wherein the volume of voidspace is between approximately 3.5 cm³/gram and 7 cm³/gram.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space having a measurable volume, and whereinthe void space volume is between approximately 80% and 90% of ameasurable volume of the biomimetic scaffold.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space having a measurable volume, and whereinthe scaffold has a permeability of between approximately 1400 and 2600millidarcy.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space having a measurable volume, wherein themultitude of interconnected pores have a tortuosity of approximatelybetween 5 μm/μm and 45 μm/μm, wherein the tortuosity defines a ratio ofactual flow path length to straight distance between first and secondends of the microporous matrix.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space having a measurable volume, a structuresupporting the microporous matrix; and wherein the void space surfacearea to volume support structure volume is between approximately 7,000cm²/cm³ and 14,000 cm²/cm³.

According to another aspect of the disclosure, a composite scaffoldcomprises: a support structure defining an interior space; and amicroporous matrix disposed within the interior space of the supportstructure, wherein the microporous matrix comprises a plurality ofinterconnected pores having a median pore size of between approximately12 μm to 50 μm.

According to another aspect of the disclosure, a composite scaffoldcomprises: a support structure defining an interior space; and amicroporous matrix disposed within the interior space of the supportstructure, the microporous matrix having a multitude of interconnectedpores collectively defining void space; wherein at least approximately60% of the void space comprises pores having a size dimension of 10 μmor greater.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores collectively defining void space opening to an exterior surface ofthe microporous matrix; and a structure supporting the microporousmatrix; the biomimetic scaffold having a measurable dry weight valuerepresenting a weight of the biomimetic scaffold in a substantially drystate and a measurable dry volume value representing a volume of thebiomimetic scaffold in a substantially dry state, wherein an increase ofbetween approximately 200% and 600% of the weight value of thebiomimetic scaffold from fluid absorption changes the dry volume valueof the biomimetic scaffold between approximately 0% and 10%.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores collectively defining void space opening to an exterior surface ofthe microporous matrix; and a structure supporting the microporousmatrix; the composite scaffold having a measurable dry weight valuerepresenting a weight of the composite scaffold in a substantially drystate and a measurable dry length value representing a dimensionalparameter of the composite scaffold in a substantially dry state,wherein an increase of between approximately 200% and 600% of the weightvalue of the composite scaffold from fluid absorption changes the drylength value of the composite scaffold by less than betweenapproximately 0% and 3%.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores collectively defining void space opening to an exterior surface ofthe microporous matrix; and a structure supporting the microporousmatrix; the composite scaffold having a measurable dry weight valuerepresenting a weight of the composite scaffold in a substantially drystate and a measurable cross sectional profile value representing adimensional parameter of the composite scaffold in a substantially drystate, wherein an increase of between approximately 200% and 600% of theweight value of the composite scaffold from fluid absorption changes thecross sectional profile value of the composite scaffold by betweenapproximately 0% and 10%.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores collectively defining void space opening to an exterior surface ofthe microporous matrix; and a structure supporting the microporousmatrix; wherein a smallest dimension of the composite scaffold is athickness dimension approximately greater than or equal to 1 mm, andwherein the composite scaffold has a swelling profile measurable by aless than or equal to 10% change in measured wet thickness of thecomposite scaffold in comparison to a measured dry thickness of thecomposite scaffold.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores collectively defining void space opening to an exterior surface ofthe microporous matrix; and a structure supporting the microporousmatrix; the composite scaffold having a measurable dry weight valuerepresenting a weight of the composite scaffold in a substantially drystate, wherein the microporous matrix is less than approximately 6% ofthe dry weight value of the composite scaffold.

According to another aspect of the disclosure, a scaffold comprises: athree-dimensional support structure having a length dimension extendingbetween first and second ends of support structure, the supportstructure comprising first and second outer layers spaced apart by adistance therebetween defining a thickness dimension normal to thelength dimension, and a plurality of spacer elements connecting thefirst and second outer layers to maintain separation therebetween;wherein the thickness dimension of the support structure changes lessthan approximately 35% upon elongation of the length dimension byapproximately 13%.

According to another aspect of the disclosure, a scaffold comprises: athree-dimensional support structure having a length dimension extendingbetween first and second ends of support structure and defining across-sectional area normal to the length dimension, the supportstructure comprising first and second outer layers spaced apart todefine an interior space volume therebetween, and a plurality of spacerelements extending through the interior space volume between the firstand second layers and attached therebetween to maintain separation ofthe first and second layers; wherein the cross-sectional area changesless the approximately 5% upon elongation of the length dimension byapproximately 13%.

According to another aspect of the disclosure, a scaffold comprises: athree-dimensional support structure having a length dimension extendingbetween first and second ends of support structure and defining a widthdimension normal to the length dimension, the support structurecomprising first and second outer layers spaced apart by a distancetherebetween defining a thickness dimension normal to the lengthdimension and the width dimension, and a plurality of spacer elementsconnecting the first and second outer layers to maintain separationtherebetween; wherein the width dimension of the support structurechanges less than approximately 5% upon elongation of the lengthdimension by approximately 13%.

According to another aspect of the disclosure, a scaffold structurecomprises: first and second outer layers having length dimensionsdefined by respective first and second ends thereof and defining aninterior space therebetween, each of the first and second outer layerscomprising a plurality of interconnected wales extending substantiallyparallel to the respective length dimensions; a plurality of spacerelements extending substantially normal to the respective lengthdimensions through the interior space and attached to each of the firstand second outer layers proximate one of the plurality of wales, theplurality of spacer elements at least partially partitioning theinterior space into a plurality of channels extending along therespective length dimensions of the first and second outer layers.

According to another aspect of the disclosure, a composite scaffoldhaving a measurable volume comprises: a microporous matrix having amultitude of interconnected pores opening to an exterior surface of themicroporous matrix and collectively defining void space, wherein thecomposite scaffold has a density of approximately between 0.05 g/cc and0.75 g/cc, wherein the density is defined as the mass per unit volume ofthe composite scaffold.

According to another aspect of the disclosure, a composite scaffoldhaving a measurable volume comprises: a microporous matrix having amultitude of interconnected pores collectively defining void spaceopening to an exterior surface of the microporous matrix; and astructure supporting the microporous matrix; wherein the compositescaffold has a ratio of total surface area to volume of approximatelybetween 160,000:1 and 190,000:1, wherein the ratio defines the surfacearea of the scaffold to the volume the composite scaffold excluding thevoid space.

According to another aspect of the disclosure, a scaffold comprises: athree-dimensional support structure extending along an axis betweenfirst and second ends of support structure, the support structurecomprising first and second layers spaced apart to define an interiorspace volume therebetween, and a plurality of spacer elements extendingthrough the interior space volume between the first and second layersand attached therebetween to maintain separation of the first and secondlayers and defining a cross-sectional normal the axis; and a microporousmatrix in the interior space and having a multitude of interconnectedpores collectively defining void space between first and second ends ofthe support structure; wherein at least approximately 60% of the voidspace comprises pores having a size dimension of at least 10 μm orgreater; and wherein a volume of the void space is between approximately3.0 cm³/gram and 9.0 cm³/gram.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space; and a structure supporting themicroporous matrix; the composite scaffold having a substantiallyrectangular cross-section defined by exterior sides wherein a pluralityof the interconnected pores are open to one of the exterior sides andhave a largest dimension oriented relative to the one exterior side. Inone embodiment, the plurality of the interconnected pores have a largestdimension oriented between approximately between 45° and 135° relativeto the one exterior side.

According to another aspect of the disclosure, a scaffold comprises: athree-dimensional support structure having a length dimension defined byfirst and second ends thereof and a thickness dimension, normal to thelength dimension, defined by first and second outer layers separated bya space, and a plurality of spacer elements extending through the spaceand connecting the first and second outer layers; wherein the void spacesurface area to measurable volume is between approximately 500 cm²/cm³and 7,000 cm²/cm³

According to another aspect of the disclosure, a composite scaffoldoccupying a measurable volume and comprises: a microporous matrix havinga multitude of interconnected pores collectively defining void spacehaving a surface area; and a structure supporting the microporousmatrix; wherein the void space surface area to measurable volume isbetween approximately 5,000 cm²/cm³ and 16,000 cm²/cm³

According to another aspect of the disclosure, a composite scaffoldcomprising: a microporous matrix having a multitude of interconnectedpores opening to an exterior surface of the microporous matrix andcollectively defining void space; and a structure supporting themicroporous matrix; herein a surface area of the composite scaffold isbetween approximately 0.3 m²/gram and 15 m²/gram.

According to another aspect of the disclosure, a method of ligament ortendon injury repair with a composite scaffold comprises: A) providing acomposite scaffold comprising: i) first and second layers spaced apartto define an interior space therebetween and a plurality of spacerelements extending through the interior space and attached to the firstand second layers; and ii) a microporous matrix having a multitude ofinterconnected pores disposed within the interior space, and B)pre-tensioning the composite scaffold along a length dimension thereof;C) attaching the composite scaffold to an allograft or autograft tendonor a damaged or torn ligament or tendon.

According to another aspect of the disclosure, a method of making acomposite scaffold comprises: A) constructing a three-dimensionalsupport structure extending along a length dimension between first andsecond ends thereof and defining an interior space within the supportstructure; and B) forming a microporous matrix within the interiorspace, the microporous matrix having a multitude of interconnected poresin fluid communication with exterior surfaces of the support structure,wherein a plurality of the interconnected pores are oriented relative tothe dimensional characteristics of the support structure. Inembodiments, the plurality of interconnected pores are oriented radiallyinward into the interior space from exterior surfaces of the supportstructure. In embodiments, the plurality of interconnected pores areoriented towards the length dimension of the support structure.

According to another aspect of the disclosure, a composite scaffoldcomprises: a support structure having an exterior profile defining aninterior space and extending along a length dimension between first andsecond ends thereof; a microporous matrix disposed within the interiorspace having a multitude of interconnected pores opening exteriorly ofthe support structure; wherein a plurality of the interconnected poresare oriented relative to the dimensional characteristics of the supportstructure.

According to another aspect of the disclosure, a composite scaffoldcomprises: a microporous matrix having a multitude of interconnectedpores collectively defining void space opening to an exterior surface ofthe microporous matrix; and a structure supporting the microporousmatrix; the composite scaffold having a measurable dry weight valuerepresenting a weight of the composite scaffold in a substantially drystate, wherein the microporous matrix is less than approximately 6% ofthe dry weight value of the composite scaffold.

In embodiments, the second support matrix, e.g. the sponge, degradesbetween approximately two to twelve times faster than the first supportmatrix based on either mass loss or molecular weight loss. The compositescaffold may have a degradation profile with greater than or equal to50% strength retention for at least approximately two weeks afterimplantation and a mass loss of 100% mass loss between approximately sixand twelve months or longer after implantation.

In embodiments, a higher density or mass of the support matrix providesthe primary and bulk structure of the disclosed scaffold, in comparisonto the more porous matrix disposed therein. More specifically, the firstand second support matrixes have different densities or mass componentsrelative to each other. In one embodiment, the first support matrix,e.g., the textile, has a measurable mass or density which is greaterthan or equal to one times that of the mass or density of the secondsupport matrix, e.g. the sponge.

In the disclosed embodiment, the pore structure of the microporousmatrix is designed to facilitate cellular attachment, proliferation, andingrowth throughout the scaffold dimensions. In embodiments, the facesof the device, the secondary matrix, or pore structure could beengineered in architecture to encourage cellular migration in a certaindirection, or to encourage the formation of aligned tissues such asconnective tissues. In other embodiments the surfaces of the devicemight differ from each other in physical or chemical characteristics toreflect use in specific anatomic locations—i.e. one side to encourageintegration with bone while the other to encourage tendon; or one sideto encourage abdominal wall regeneration but the other side to preventadhesions of internal organs.

In embodiments, the composite scaffold disclosed herein provides ameasurably high surface area to volume ratio, compared to existingcommercially available devices, to facilitate more rapid and greaterquantity of cell infiltration and tissue ingrowth within the compositescaffold. More specifically, based predominantly on the first supportmatrix, e.g., the textile, surface area of the fiber to volume of thedevice ratio, calculated using scaffold denier, polymer density anddimensions, greater than 10 times.

In embodiments, the scaffold may have ends that narrow and transitioninto suture-like dimensions or are modified, e.g. stitched or knotted,to attach to conventional suture used in the procedures describedherein. In other embodiments, the first support matrix, e.g., thetextile, has ends or edges that are modified to be heat set orembroidered or impregnated with other materials to facilitate betterhandling, better integration with existing tissue and to further reducedimensional distortion of the scaffold under pressure, tensile, or shearforces. In other embodiments, a monofilament or multifilament suture ofany material may pass through the scaffold lengthwise and exit bothends, and be attached or fixed to the scaffold.

In other embodiments selected sections of the scaffold may be repeated,either randomly or with fixed frequency to increase or decrease thedensity of the scaffold by increasing or decreasing the density of thetextile, for example, by a change in the textile pattern of the firstsupport matrix. In still other embodiments, such repeating regions maybe chosen to alter the surface finish of the scaffold by altering thesmoothness or roughness, of the exterior surface of the scaffold toenhance acceptance of the scaffold once implanted.

In one embodiment, the composite scaffold comprises just a singlethree-dimensional support matrix which may be the same or different thaneither of the first or second support matrices described herein and mayhave any of the characteristics of the composite scaffold describedherein.

Also disclosed is a method of treatment of ligament or tendon injurywherein a scaffold is attached to an allograft or autograft tendon andused to replace a damaged ligament or tendon, or, the scaffold is usedto augment a damaged or torn ligament or tendon. Methods of use mayinclude preparation of the scaffold with a solution to enhance itsperformance, pretensioning of the scaffold, and/or fixing the femoralend and independently tensioning and fixing a tendon and graft in thetibial tunnel.

In use, the composite scaffold may be utilized in a wide array ofmedical procedures including to reinforce a suture repair, stand alonerepair or reconstruction, or reconstruction using a tissue graft and forfixation purposes. Reinforcement of a repair or reconstruction using thecomposite scaffold may be applicable to the knee, ankle, shoulder, hip,elbow, foot, and hand, and non-musculoskeletal soft tissue.

In accordance with another aspect of the disclosure, a graft preparationtable provides a surface and fixation mechanisms that allow forindependent tensioning of tissue, e.g. tendon or ligament, and compositescaffold either prior to or during an implantation procedure.

In accordance with another aspect of the disclosure, a fixation deviceallows tissue, e.g. tendon or ligament, and composite scaffold to beattached to each other avoiding the need for whip stitching. Such devicemay comprise a clip with legs that go through graft and tendon.

DESCRIPTION THE DRAWINGS

The various features and advantages of the present invention may be morereadily understood with reference to the following detailed descriptiontaken in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1A is a conceptual illustration of a composite scaffold inaccordance with the disclosure;

FIG. 1B is a photograph of a composite scaffold in accordance with thedisclosure;

FIG. 1C is a photograph of a composite scaffold in accordance with thedisclosure;

FIG. 2A is a conceptual illustration of knit pattern usable for exteriorlayers of the composite scaffold in accordance with the disclosure;

FIG. 2B is a conceptual illustration of an alternative knit patternusable for exterior layers of the composite scaffold in accordance withthe disclosure;

FIG. 2C is a conceptual illustration of the yarn components patternscomprising the exterior layers of FIGS. 2A-B in accordance with thedisclosure;

FIG. 2D is a conceptual illustration of a perspective view of textilepatterns for a pair of composite scaffolds useful for ACL and rotor cuffprocedures in accordance with the disclosure;

FIG. 3A is a photograph of a plan view of a composite scaffold having atleast on exterior layer made in accordance with the pattern of FIG. 2Ain accordance with the disclosure;

FIG. 3B is a photograph of a side view of the composite scaffold of FIG.3A;

FIG. 4A is an SEM photograph of a plan view of a composite scaffoldhaving at least on exterior layer made in accordance with the pattern ofFIG. 2A in accordance with the disclosure;

FIG. 4B is an SEM photograph of a side view of the composite scaffold ofFIG. 4A;

FIG. 4C is an SEM photograph of a perspective, cross-sectional view ofthe composite scaffold of FIG. 4A as seen along axis 4A-4A in FIG. 4A;

FIG. 5A is a perspective view of a mold useful in making a compositescaffold in accordance with the disclosure;

FIGS. 5B-C are top and side plan views, respectively, of another molduseful in making a composite scaffold in accordance with the disclosure;

FIG. 5D illustrates graphically the relationship of temperature, timeand pressure during the lypholization process in accordance with thedisclosure;

FIGS. 6A-6C are SEM photograph of a sagittal cross-sectional view of themicroporous matrix of the composite scaffold of FIG. 1C as taken alongline A-A within the in accordance with the disclosure;

FIG. 6D is an SEM photograph of a coronal cross-sectional view of themicroporous matrix of the composite scaffold of FIG. 1C as taken alongline B-B within the in accordance with the disclosure;

FIG. 6E is an SEM photograph of a transverse cross-sectional view of themicroporous matrix of the composite scaffold of FIG. 1C as taken alongline B-B within the in accordance with the disclosure;

FIG. 6F is an SEM photograph of a sagittal cross-sectional view of themicroporous matrix of the composite scaffold of FIG. 1C as taken alongline A-A within the in accordance with the disclosure;

FIG. 6G is an SEM photograph of a coronal cross-sectional view of themicroporous matrix of the composite scaffold of FIG. 1C as taken alongline B-B within the in accordance with the disclosure;

FIG. 6H is an SEM photographs of a transverse cross-sectional view ofthe microporous matrix of the composite scaffold of FIG. 1C as takenalong line B-B within the in accordance with the disclosure;

FIG. 6I is an SEM photographs of a sagittal cross-sectional view of themicroporous matrix of the composite scaffold of FIG. 1C as taken alongline A-A within the in accordance with the disclosure;

FIG. 7A is an SEM photograph of a typical microporous matrix attached toa fiber support structure of a composite matrix in accordance with thedisclosure;

FIG. 7B is an SEM photograph of a typical microporous matrix attached toa fiber support structure of a composite matrix in accordance with thedisclosure;

FIG. 7C is an SEM photograph of the exterior surface of the typicalmicroporous matrix of a composite scaffold in accordance with thedisclosure;

FIG. 8 illustrates graphically test data defining the relationship ofthe cumulative total pore surface area relative to pore diameter inaccordance with the disclosure;

FIG. 9 illustrates graphically the relationship of the cumulative totalpore volume relative to pore diameter for a number of composite scaffoldsamples as well as only the textile only support structure in accordancewith the disclosure;

FIG. 10 illustrates graphically the relationship of the compositescaffold in relation to Mercury pressure for a number of compositescaffold samples as well as only the textile only support structure inaccordance with the disclosure;

FIG. 11 illustrates graphically the relationship of the distribution ofpore diameter relative to the logarithmic differential volume inaccordance with the disclosure;

FIG. 12 illustrates graphically the relationship of load versusextension for both a solo tendon and a tendon augmented with a compositescaffold in accordance with the disclosure;

FIG. 13A is a cross sectional microscopic view of the composite scaffoldof FIG. 1C illustrating the porous matrix relative to the support matrixin accordance with the disclosure;

FIG. 13B is a cross sectional microscopic view of the composite scaffoldof FIG. 1C hydrated with blood and illustrating how red blood cellsfully infiltrate a collagen sponge porous matrix in accordance with thedisclosure;

FIG. 14 is a photograph of the composite scaffold for MPFL repair orreconstruction in accordance with the disclosure;

FIG. 15 illustrates conceptually lapsed image of a circular textilestructure a circular textile structure in various stages of manufacturein accordance with the disclosure;

FIG. 16 illustrates conceptually how a disclosed composite may beutilized for augmented ACL repair, stabilization or reconstruction inaccordance with the disclosure; and

FIG. 17 illustrates graphically the relationship of the distribution ofpore diameter relative to percentage of pores as measured in accordancewith the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the systems and methods are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views.Throughout this description, the phrase “in embodiments” and variationson this phrase generally is understood to mean that the particularfeature, structure, system, or method being described includes at leastone iteration of the disclosed technology. Such phrase should not beread or interpreted to mean that the particular feature, structure,system, or method described is either the best or the only way in whichthe embodiment can be implemented. Rather, such a phrase should be readto mean an example of a way in which the described technology could beimplemented, but need not be the only way to do so. Further, wordsdenoting orientation such as “top”, “bottom”, “side”, “lower” and“upper”, and the like, as well as references on a specific axis inthree-dimensional space are merely used to help describe the location ofcomponents with respect to one another. No words denoting orientationare used to describe an absolute orientation, i.e., where an “upper”part must always be on top.

Referring to FIGS. 1A-6D, a composite scaffold 10 comprises a firstthree-dimensional support matrix, and a second matrix integrally formedwith one another to form the composite scaffold 10 which maximize thesurface area to volume ratio and surface area per weight ratios of thescaffold. Referring to FIG. 1A, the first matrix, in embodiments, may beimplemented with a support structure 5 comprising a first outer layer 12and a second outer layer 14 spaced apart to define an interior voidspace 16 therebetween. A plurality of spacer elements 18 extend betweenfirst outer layer 12 and a second outer layer 14 to maintain separationof the layers. In embodiments, each of layers 12, 14, and spacerelements 18 may be implemented as a three-dimensional textile structure,each having different geometries, fibers, or material compositions. Forexample, any of outer layers 12, 14, and spacer elements 18 may beimplemented with a textile of multifilament fibers and/or monofilamentfibers. Support layers 12 and 14 may be implemented as substantiallyplanar three dimensional textile comprising multi-layer knitted surfacesand spacer elements 18 may be implemented with interconnecting yarns inthe “Z” direction normal to the planes of layers 12 and 14 providesupport to prevent collapse.

The support structure 5 is intended to provide mechanical support to thegrowing neo tissue and to provide resistance to compression such thatthe area intended for new tissue formation is maintained during patientmovement and activity. As such the support structure 5 providesextensional strength in its long axis and stiffness to resistcompression in the “z direction”.

In embodiments, support structure 5 may be formed from any of 30-150denier multifilament fiber, 30-150 denier monofilament fiber, or 30-150denier composite yarn, or any combination thereof, e.g., a combinationof multifilament and monofilament fibers, and may be optionally coatedwith an anti-adhesion material. Unfinished edges of the scaffold 10maybe sealed or secured using methods inclusive, but not limited to,heat setting or embroidery. In one embodiment, support structure 5 isfabricated from 75-denier 30-filament Poly-L-Lactic Acid (PLLA) with apolymer density of 1.25 g/cc. Yarns may be braided over a twisted fiberyarn to provide higher stiffness yarns for use as a lay in as describedbelow.

In embodiments, one or both of outer layers 12 and 14 of supportstructure 5 may be implemented with a warp knit open pillar stitch 22using double yarns, as illustrated in FIGS. 2A and 2C, resulting in thetextile layers illustrated in FIG. 3A. As can be seen from FIGS. 2A and3A, the exterior layer comprises a series of wales connected by singleweft lay-in 26 yarn and having double 0∘ straight lay-in yarns 24 onboth sides inserted in the pillar structure, as illustrated in FIG. 2A.The pattern of the first outer layer 12 and second outer layer 14 may bethe same or different. In embodiments, both outer layers 12 and 14 mayhave the same number of wales with spacer elements 18 connecting similarcorresponding wales in each of layers 12 and 14. In embodiments, outerlayers 12 and 14 may have different number of wales with spacer elements18 connecting wales in each of layers 12 and 14.

As used herein, a wale is “a column of loops” lying lengthwise in thefabric. Each wale may be a single or double fiber to increase strength,but consequently increasing bulk. Increasing the number of wales, or thenumber of yarns per wale, will result in increasing the ultimate tensilestrength of the fabric. By adjusting the number of wales, the width ofthe fabric can changed, which allows the same textile design to beapplied to narrow applications, such as for ACL augmentation. e.g. 5 mmwide, to moderately wide applications, such as for Rotator Cuff, e.g. 23mm wide, to very wide applications, such as for Hernia, e.g. 200 mmwide. A method of increasing ultimate tensile strength, resistance toelongation and initial stiffness can be achieved by the addition of 0°straight lay-in yarns to the technical faces of the fabric. These lay-inyarns are incorporated into each wale in a linear fashion.

A machine that has been used to manufacture the scaffold 10 is a KarlMayer Double Needle Bar Warp Knitting Machine. These machines arecomputer controlled and allow modification of many parameters to effectchanges to the textile properties. Key variables include the number ofwales, the number of yarns per wale, addition of In-lay yarns to wales,In-lay yarn design, and number of yarns per in-lay. The ability of thefabric to stretch under tensile load can be influenced by, for example,knitting together every two wales rather than every three walestogether.

Referring to FIGS. 3B and 4B, spacer elements 18 may be implemented witha plurality of yarns in the “Z” direction, normal to the planes in whichlayers 12 and 14 exist, that connect layers 12 and 14 and providesupport to prevent collapse. In embodiments, each of layers 12 and 14may have the same number of wales and spacer elements 18 may connectcorresponding wales in each of layers 12 and 14. In other embodiments,spacer elements 18 may cross diagonally between different wales oflayers 12 and 14. Spacer elements 18 may comprise yarns which may bemonofilament, multifilament, or multifilament and/or textured.

One or both of layers 12 and 14 may be implemented using the textilepattern illustrated in FIG. 2B. Other textile patterns suitable forlayers 12 and 14 may include including Full Tricot, Locknit, andQueenscord, Single Atlas, Jersey, reverse jersey, miland interlock,Milano, half Milano, etc. Variations of warp knit surface design can beutilized to adjust the dimensions, density and mechanical properties ofthe layers 12 and 14 including any of: surface design, number of wales,number of yarns per wale, addition of in-lay yarns to wales, in-lay yarndesign, number of yarns per in-lay, lengthening or decreasing quality(machine parameter), or lengthening or decreasing gap (machineparameter).

An alternative method to warp knitting is the use of a V-Bed knittingmachine, such as a Whole Garment Knitting machine, or use of a doublerapier loom or a fly-shot loom to generate a woven 3D spacer fabric.

Adding pull threads between knitted panels spreads tension and keepspanels together during the manufacturing process until the pull threadis removed, without tearing or catching. These pull threads can beeither mechanically removed, or dissolved away in a scour process.

In an illustrative embodiment, a support structure number five,implemented with a three-dimensional textile may have the physicalparameters as illustrated in FIG. 1 below.

Textile-Only Surface Area (m2/g) 0.2315 Mass (g) 0.0684 Sample SA (m2)0.0158 Skeletal Density (g/cc) 1.24 Skeletal Volume (cm3) 0.0552 SA:Vol(cm2:cm3) 2871

A scaffold having the above physical values, and defining a void spacebetween the first and second outer layers 12 and 14, respectively,through which plurality of spacer elements 18 extend, may be calculatedto have a measurable void space surface area to volume ratio of betweenapproximately 500 cm²/cm³ and 7,000 cm²/cm³

Subsequent to manufacture the scaffold textile may be scoured to cleanit and remove any finishes that may have been used. The method ofscouring can include the use of water, solvent and water solventmixtures. The fabric may be washed constrained or unconstrained. Thefabric may also be treated with an agent to modify its surfacecharacteristics, for example, to influence its hydrophilicity. Variousagents can be used for this including polyethylene glycols. The surfacemay also be treated to improve cell adhesion by agents such as fibrin.Where a portion of the scaffold is intended to be placed into contactwith a bone region the surface of the fibers may be coated with acalcium phosphate, hydroxyapatite or bioactive glass or growth factorsuch as a bone morphogenetic protein, and demineralized bone matrix.

In embodiments, the composite scaffold 10, or any portion thereof,including layers 12 and 14 or spacer elements 18, may comprise anycombination of synthetic bioresorbable polymers, natural polymers and/oradditives. Synthetic bioresorbable polymers suitable for use as part ofthe composite scaffold may include, homopolymers, copolymers, or polymerblends of any of the following: polylactic acid, polyglycolic acid,polycaprolactone, polydioxanone, polyhydroxyalkanoates, polyanhydrides,poly(ortho esters), polyphosphazenes, poly (amino acids),polyalkylcyanoacrylates, poly(propylene fumarate), trimethylenecarbonate, poly(glycerol sebacate), poly(glyconate), poly(ethyleneglycol), poly(vinyl alcohol) and polyurethane, or any combinationthereof. Natural polymers suitable for use as part of the compositescaffold may include silk, collagen, chitosan, hyaluronic acid,alginate, and an amnion-derived matrix.

Composite Scaffold Dimensions

In embodiments, the composite scaffold 10 may have a thickness, i.e. thevertical height dimension of the scaffold as opposed to the largerlength and width dimensions, between approximately 0.5 mm to 5 mm, and,even more preferably between approximately 1 mm to 3 mm. Even morepreferably, the scaffold may have a minimum thickness of approximatelygreater than or equal to 1 mm. In embodiments, the thickness of thescaffold 10 may be uniform along a length thereof or may vary in arepeating or non-repeating manner, depending on the particularapplication for which the scaffold will be utilized.

In embodiments, the disclosed composite scaffold 10 may have widthdimensions between approximately 2 mm to 1000 mm, depending on theparticular application for which the scaffold will be utilized. Inembodiments, the width of the disclosed scaffold may be uniform or mayvary in a repeating or non-repeating manner, depending on the particularapplication for which the scaffold will be utilized. For example, ascaffold 10 may have ends were in the width of the scaffold narrows anddimensionally transitions into a suture-like dimension or is modified toattach to conventional suture used in the procedures described herein.

In embodiments, the disclosed composite scaffold may have lengthdimensions between approximately 2 to 1000 mm, and, even more preferablygreater than or equal to approximately 10 inches, again, depending onthe particular application for which the scaffold will be utilized. Inembodiments, the disclosed scaffolds may be manufactured in differentincremental lengths or may be manufactured in lengths which may be cutor customized by practitioner as desired. FIG. 4B is an SEM photographof a side view of the composite scaffold 10 may have length dimensionand formed from a pair of outer layers 12 and 14 separated by aplurality of spacer elements 18. The photograph of FIG. 4B was takenwith a Philips/FEI XL30 ESEM Scanning Electron Microscope (SEM) with a 1mm scale legend shown on the image and distances along the axis of thelength dimension between spacer yarn, indicated by reference lines 1-23.Table 1 displays each reference line and its respective distance valuein micrometers as well as an average distance. As can be seen from Table1, the average distance along the axis of the length dimension betweenspacer yarns is approximately is between spacer yarns is betweenapproximately 200 μm and 300 μm.

TABLE 1 BZ3S32 ROI # Length (μm) 1 522.471 2 486.002 3 395.111 4 272.2785 171.236 6 177.801 7 221.409 8 201.073 9 213.168 10 174.469 11 137.66912 171.932 13 556.535 14 537.49 15 444.187 16 327.109 17 202.071 18216.961 19 146.15 20 173.058 21 219.813 22 141.249 23 176.63 Avg273.2987826 StDev 141.0820741

FIG. 4C is an SEM photograph of a perspective, cross-sectional view ofthe composite scaffold of FIG. 4A. The photograph of FIG. 4C was takenwith a SEM with a 1 mm scale legend shown on the image and distancesalong a width axis, normal to the axis of the length dimension, betweenspacer yarns, indicated by reference lines 1-17. Table 2 displays eachreference line and its respective distance value in micrometers as wellas an average distance. As can be seen from Table 2, the averagedistance along the width axis between spacer yarns is betweenapproximately 300 μm and 400 μm (along axis);

TABLE 2 BZ3S32 ROI # Length (μm) 1 447.624 2 372.521 3 371.068 4 374.4615 450.989 6 433.509 7 287.975 8 257.186 9 272.488 10 309.407 11 511.86112 300.123 13 336.968 14 341.38 15 416.442 16 444.514 17 477.495 Avg376.8242 StDev 76.92161

In the disclosed composite scaffold 10, the respective distances betweenspacer elements 18, e.g. the spacer yarns, create a series ofsubstantially parallel, similarly sized channels extending through thevoid between outer layers 12 and 14. These channels provide space withinthe interior of the support structure into which the microporous matrix15 may be formed, as described herein. Importantly, these channels formalong the axis of the device such that a contiguous channel existsbetween the two ends of the scaffold. Upon replacement by neo tissue,the neo tissue is substantive along the axis of the device and is henceload bearing and thus a functional tissue.

Support Structure Additives

A composite scaffold 10 made of any of the foregoing materials may becombined with additives to enhance various characteristics of thescaffold including to encourage regeneration of cell growth. SuchAdditives suitable for use as part of the composite scaffold may includebiologics including seeded cells, biological aspirates, and bio-activeagents. Seeded cells suitable for use as part of the composite scaffoldmay include adipose derived stem cells, mesenchymal stem cells, andinduced pluripotent stem cells, or any combination thereof. Biologicalaspirates suitable for use as part of the composite scaffold may includewhole blood, platelet rich plasma and bone marrow aspirate concentrate,or any combination thereof.

Bio-active agents suitable for use as part of the composite scaffold 10may include growth factors, extracellular matrix molecules and peptides,therapeutics, and osteoinductive or osteoconductive agents, or anycombination thereof, and may be added to the support structure 5 beforeformation of the microporous matrix 15 or thereafter.

Growth factors suitable for use as part of the composite scaffold mayinclude transforming growth factor-beta superfamily (e.g. transforminggrowth factor-beta, bone morphogenetic proteins), insulin-derived growthfactor, platelet-derived growth factor epidermal growth factor,Interleukin 1-receptor antagonist, fibroblast growth factor and vascularendothelial growth factor, or any combination thereof.

Extracellular matrix molecules and peptides suitable for use as part ofthe composite scaffold may include tenascin-C, hyaluronic acid,glycosaminoglycans (e.g. chondroitin sulfate, dermatan sulfate, andheparan sulfate), fibrin, thrombin, small leucine rich peptides (e.g.decorin and biglycan), fibronectin, elastin andarginine-glycine-aspartate (RGD) peptide, or any combination thereof.

Therapeutics suitable for use as part of the composite scaffold mayinclude non-steroidal anti-inflammatories (NSAIDs) (e.g., aspirin,ibuprofen, indomethacin, nabumetone, naproxen, and diclofenac),steroidal anti-inflammatories (e.g., cortisone and hydrocortisone),antibiotics or antimicrobial agents, or any combination thereof.

Osteoinductive or osteoconductive agents suitable for use as part of thecomposite scaffold may include tricalcium phosphate, hydroxyapatite, andbioactive glass, or any combination thereof.

Microporous Matrix

An optional microporous matrix 15 may be formed within the interior voidspace 16 of composite scaffold 10. The microporous matrix 15 issupported and retained by support structure 5 and provide a support forcells to populate, proliferate. The microporous matrix 15 is resorbableor degradable and is designed to be rapidly replaced by neo tissue. Amicroporous matrix made from the materials described herein, on its ownwould not have the mechanical strength characteristics to be usable,both in terms of tensile strength and resistance to compression.

In embodiments, disclosed is a method of making a composite scaffoldcomprising constructing a three-dimensional support structure extendingalong a length dimension between first and second ends thereof anddefining an interior surface within the support structure; and forming amicroporous matrix within the interior surface, the microporous matrixhaving a multitude of interconnected pores 60 in fluid communicationwith exterior surfaces of the support structure. The microporous matrixis formed so that a plurality of the interconnected pores 60 areoriented relative to the dimensional characteristics of the supportstructure. For example, those pores closest to exterior surfaces of thecomposite matrix may be oriented substantially normal, or radiallyinward extending, relative to the closest exterior surface of thesupport structure. In addition, other of the plurality of interconnectedpores 60 may be oriented towards the length dimension of the supportstructure in a manner that mimics the orientation of spacer elements 18,e.g. spacer yarns, separating the outer layers 12 and 14.

In embodiments, microporous matrix 15 may be implemented with a highsurface area material such as any of a sponge, foam, or textured fibersor yarns, or any combination thereof. Methods for fabrication of themicroporous matrix 15 may comprise any of lyophilization, particulateleaching, open cell extrusion, solvent casting, solid-state foaming, andcrosslinking. In one embodiment, sponges/foams useful as the microporousmatrix may comprise any of freeze-dried sponge, open cell extrusion foamand particulate leached sponge, or any combination thereof.

A material suitable to implement microporous 15 is collagen, includingbovine type 1 collagen. Other materials that can be used for microporousmatrix 15, in place of or in addition to collagen, include hydrogelsbased on Polyethylene Glycol (PEG), Polycaprolactone (PCL), or Poly(glycolide-co-caprolactone) (PGCL), or a combination thereof. A collagensolution can be infiltrated into support structure 5 with the help of amold to hold the scaffold. The secondary scaffold material may also coatthe exterior surfaces of support structure 5 in an encapsulating manner.The mold, with textile and collagen solution, may be placed into a shelflyophilizer, also known as a freeze dryer that usestemperature-controlled shelves to freeze the contents of the mold to avery cold temperature, e.g. down to −55C, which creates a crystallinestructure within the collagen solution causing a matrix ofinterconnected pores to be formed within the collagen structureoccupying the interior void space 16 of support structure 5. A vacuum ispulled in the lyophilizer chamber, and the shelf temperature graduallyincreased, providing energy to the frozen solvent, allowing the processof sublimation to occur. The sublimated solvent is collected in aseparate condenser and fully removed from the inflammation. After aperiod of warming and vacuum, a highly porous, low density collagenmatrix is formed within the textile.

The porosity of the collagen within the microporous matrix 15 can beinfluenced during this process in multiple ways. Bulk porosity can beincreased or decreased by decreasing or increasing the collagen solutionweight percentage, respectively. The size of the pores can be adjustedby changing the rate of freezing in the mold. Increasing the rate offreezing decreases the average size, and decreasing the rate of freezingincreases the average size.

Since the total surface area of the pores is related to the pore size,e.g. a large quantity of small pores will have more surface area thanfewer larger pores, increasing the rate of freezing increases decreasesthe average pore size therefor increasing the total surface area, whiledecreasing the rate of freezing increases the average size thereforedecreases the total surface area of the microporous matrix. FIG. 5D is agraph illustrating the relationship of temperature, pressure and timeduring the during the lypholization process.

Variations in mold material, including Delrin, Aluminum, StainlessSteel, or other materials, transfer heat differently and can result indifferent microporous matrix structures by altering crystallization inthe collagen solution as it freezes. For example, a mold made of Delrin,a thermoplastic used in precision parts manufacturing, transfers heatmore slowly causing larger pore sizes to form within the collagensolution. Conversely, a mold formed of aluminum transfers heat veryquickly resulting in a microporous matrix with relatively small sizepores. A mold made of stainless steel transfers heat more slowly thanaluminum and results in larger pores than those generated with analuminum mold, but smaller than those generated with a Delrin mold.

In addition, adjusting the thickness of the mold, between the bottomsurface of the mold and the bottom of the cavity has a similar effect ofincreasing or decreasing heat transfer speed, which can result indifferent microporous matrix structures. In embodiments, or the moldsshown in FIGS. 5A and 5B are made from stainless steel and have thecavity dimensions listed in table 2 below, wherein the 5×260 mm columnof dimensions refers to the mold 50 illustrated in FIG. 5A and the 23×30mm column of dimensions refers to the mold 57 illustrated in FIG. 5B.Mold 50 defines a plurality rectangular cavities 52 and has clamps 54with pins 55 securable at the ends thereof. Mold 57 includes an array ofrectangular cavities 59 and threw holes 53.

TABLE 2 5 × 260 mm 23 × 30 mm Cavity Width 5.21 23.20 Cavity Length260.00 30.20 Cavity Depth 4.09 8.00 Distance from bottom of 4.70 4.70cavity to bottom of mold

The mold illustrated in FIG. 5A utilizes end clips made of Delrin, whichare securable to the main mold body and which may be used to clamp thetextile scaffolds during the lypholization process.

In an illustrative embodiment the cavity 52 of mold 50 have asubstantially rectangular cross-sectional shape. Other cross-sectionalshapes may be utilized to maximize the contact between surface area ofthe support structure five during the process of forming the microporousmatrix therein. In particular, scaffolds having any of a D-shape,U-shape, O-shape, or C-shape may be utilized during the lypholization tomaximize the surface area of the shape of the scaffold and furtherfacilitate orientation of the pores with the microporous matrix thelypholization process. In particular, for a support structure fivehaving a cylindrical or tubular shape, tube shaped molds, whetheroriented horizontally or vertically may be utilized during thelypholization process.

Alignment of pores relative to a dimension of the scaffold can becreated via contact with the mold surfaces. As illustrated in thecross-sectional SEM photographs of FIGS. 6D-E, 6G-H, it is seen thatpores within the microporous matrix 15 form, proximate the mold surfaceperpendicularly to the plane of contact with the mold. In embodiments,applicant has found that pores may be oriented between proximally 45 and135° to the plane of contact with the mold. In embodiments, with a moldsimilar to that illustrated in FIG. 5A, a substantial number of poreswill orient normal to the contact surfaces with the mold interiortowards the center of the support structure 5. Such orientation furtherfacilitates the ingrowth of cells into the composite scaffold 10 morerapidly.

An alternative mold design utilizes a similar cavity as above, but withthe addition of a securely fashioned and air-tight top lid. Vacuum, orpressure, or other means may be used to fill the mold with collagensolution from one end, similar to injection molding, and release trappedgasses at another end, helping to further align the collagen fibersduring the injection process.

An additional alternative mold design uses cavities that place thetextile on its side, so that the faces of the textile are perpendicularto the bottom face of the mold. An additional alternative mold designmay use cavities that have a “U” shaped cross-sectional profile oranother shape, which will create a finished scaffold shaped moreapplicably for a specific type of implantation.

There are various methods to manufacture may be used to create amicroporous matrix within the void space of the textile supportstructure, including salt leaching, gas extrusion, and other methodsusing either high pressure, or vacuum, and gasses.

The resorption and mechanical characteristics of the microporous matrixmay be further modified by crosslinking. Generally, materials used forcrosslinking have potential cyctotoxicity so being able to use lowerlevels is greatly beneficial. It is a benefit of the disclosed procedurethat the use of the support structure 5 allows the microporous matrix 15to utilize a low level of crosslinking. The 3D textile, infilled with adry, highly porous and low-density collagen microporous matrix, isremoved from the mold cavities and placed into a sealed chamber on apermeable shelf, such as a wire rack. A formaldehyde and ethanolsolution is poured into a tray, and this tray is placed under the rackof scaffold, and the chamber door sealed. The tray fully encompasses thebase dimensions of the chamber (L×W) and the vapor from the solution isused to crosslink the collagen within the 3D textile. After a set time,the tray is removed, and the product is moved into an aeration chamber,in which clean, dry air, or alternatively, another gas such as Nitrogen,is pumped through and out of the chamber, which effectively stops thecrosslinking process. Crosslinking of the collagen can be increased byincreasing the time in the chamber, increasing concentration offormaldehyde in the ethanol solution, or reducing the aeration.Likewise, crosslinking can be decreased by decreasing time in thechamber, decreasing concentration of formaldehyde in the ethanolsolution.

Alternatively a chemical cross linking agent may be added to thecollagen solution. These agents may include, but are not limited to,various concentrations of aldehydes such as glutaraldehyde, genipin,1-ethyl-3-(3-dimethylaminoipropyl) carbodiimide (EDC), andEDC/N-hydroxysuccinimide (EDC/NHS). An additional alternative mode ofcrosslinking may come in the form of photochemically activatedcrosslinking, which may involve the use of UV or visible light totrigger a crosslinking process with or without a crosslinking initiator.

Composite Scaffold Mechanical Characteristics

The mechanical characteristics of the composite scaffolds 10 disclosedherein, result in a composite scaffold optimized for use in a wide arrayof medical procedures including to reinforce a suture repair, standalone repair or reconstruction, or reconstruction using a tissue graftand for fixation purposes. Composite scaffolds 10 made in accordancewith the description herein as well as Examples 1, 2 and 3 were tensiletested using a Mark-10 Tensile Tester with a crosshead speed of 20mm/min, with the results listed in Table 3.

TABLE 3 Textile Cross Change Change Sectional Change Change Cross inForce Displacement % Width Thickness Area Width Thickness Section volume(N) (mm) Extension (mm) (mm) (mm²) % % Area % % 0 0  0% 4.81 3.14 15.1 11  3% 4.79 3.02 14.47  −0.4%  −3.8%  −4.2%  −2% 4.5 2  5% 4.79 2.8313.56  −0.4%  −9.9% −10.2%  −6% 11.5 3  8% 4.64 2.48 11.51  −3.5% −21.0%−23.8% −18% 22 4 10% 4.64 2.18 10.12  −3.5% −30.6% −33.0% −26% 35 5 13%4.57 2.17 9.92  −5.0% −30.9% −34.3% −26% 46.5 6 15% 4.48 2.02 9.05 −6.9% −35.7% −40.1% −31% 55 7 18% 4.44 2.02 8.97  −7.7% −35.7% −40.6%−30% 61.5 8 20% 4.38 1.91 8.37  −8.9% −39.2% −44.6% −34% 68 9 23% 4.381.86 8.15  −8.9% −40.8% −46.0% −34% 74.5 10 25% 4.35 1.81 7.87  −9.6%−42.4% −47.9% −35% 81 11 28% 4.25 1.79 7.61 −11.6% −43.0% −49.6% −36% 8812 30% 4.27 1.73 7.39 −11.2% −44.9% −51.1% −36% 94 13 33% 4.21 1.71 7.2−12.5% −45.5% −52.3% −37% 101 14 35% 4.18 1.64 6.86 −13.1% −47.8% −54.6%−39% 108.5 15 38% 4.15 1.6 6.64 −13.7% −49.0% −56.0% −40% 116 16 40%4.12 1.54 6.34 −14.3% −51.0% −58.0% −41% 124 17 43% 4.09 1.52 6.22−15.0% −51.6% −58.8% −41% 131 18 45% 4.05 1.52 6.16 −15.8% −51.6% −59.2%−41% 136.5 19 48% 3.98 1.48 5.89 −17.3% −52.9% −61.0% −42% 20 50% 3.961.48 5.86 −17.7% −52.9% −61.2% −42%

An advantage of the composite scaffold 10, and particularly, the supportstructure 5, as disclosed herein, is its ability to resist compressionupon elongation. In embodiments, as can be seen from the values in Table3 above, the width, height and cross-sectional area of thethree-dimensional textile comprising support structure 5 resistscompression upon substantial forces. In particular, for a supportstructure 5 having a cross-sectional area of approximately 9.92 mm², athickness (height) of approximately 2.17 mm and a width of approximately4.57 mm, extension of the support structure 5 along its length axis byforce of 35 N causes an approximately 13% extension of the lengthdimension of the support structure 5. In embodiments, the thicknessdimension of the support structure changes less than approximately 31%upon elongation of the length dimension by approximately 13%. Inembodiments, the cross-sectional area changes less the approximately 35%upon elongation of the length dimension by approximately 13%. Inembodiments, the width dimension of the support structure changes lessthan approximately 5% upon elongation of the length dimension byapproximately 13%.

In embodiments, a length of a support structure 5, implemented with athree-dimensional textile scaffold as disclosed herein, may have anultimate load at a percentage of elongation of the length dimensionbetween approximately 30% and 125%. In embodiments, the scaffold mayhave a yield at a percentage of elongation of the length dimensionbetween approximately 5% and 15%. In embodiments, the scaffold may havea tenacity of between approximately 0.073 grams-force/denier and 1.102grams-force/denier. In embodiments, the scaffold may have a stiffness ofapproximately between 2.5 N/mm and 25 N/mm, wherein the stiffnessdefines an extent to which the scaffold resists deformation in responseto an applied force. In embodiments, the scaffold may have a strain atfailure of approximately between 20% and 70%. In embodiments, thescaffold may have a tenacity at failure approximately between 0.3grams-force/denier and 2 grams-force/denier.

In an illustrative embodiment, the support structure 5, implemented witha three-dimensional textile scaffold 5 mm in width and 40 mm in lengthand having a thickness approximately 1 mm, or as disclosed herein, mayhave an ultimate load displacement of approximately between 5 mm and 50mm, wherein the ultimate load displacement defines a change indisplacement at an amount of load applied to the biomimetic scaffoldbeyond which the biomimetic scaffold will fail. Such test being donewith a 40 mm gauge length and in accordance with the standards set forthby the American Society for Testing and Materials (ASTM). In theillustrated embodiment, the scaffold may have a yield displacement ofapproximately between 1 mm and 8 mm, wherein the yield displacementdefines a change in displacement at which the biomimetic scaffold beginsto deform. In the illustrated embodiment, the scaffold may have a yieldforce of approximately between approximately between 20 N and 70 N,wherein the yield force defines a force at which the biomimetic scaffoldbegins to deform. In the illustrated embodiment, the scaffold may have astiffness of approximately between 2.5 N/mm and 25 N/mm, wherein thestiffness defines an extent to which the biomimetic scaffold resistsdeformation in response to an applied force. In the illustrativeembodiment, the scaffold may have an ultimate strain of approximatelybetween 20% and 70%, wherein the ultimate strain defines the deformationof the biomimetic scaffold due to stress. In the illustrated embodiment,the scaffold may have an ultimate load approximately between 100 N and200 N wherein the ultimate load is defined as the amount of load appliedto the biomimetic scaffold beyond which amount the scaffold fails. Inthe illustrative embodiment, the scaffold may have an ultimate strengthapproximately between 2.5 MPa and 20 MPa wherein the ultimate strengthis defined as a capacity of the biomimetic scaffold to withstand loadstending to elongate the biomimetic scaffold. In the illustrativeembodiment, the scaffold may have an ultimate stress approximatelybetween 2.5 MPa and 20 MPa wherein the ultimate stress is defined as amaximum value of stress that the structure can resist beyond whichmaximum value the structure fails. In the illustrated embodiment, thescaffold may have a modulus of approximately between 2.5 MPa and 70 MPa,wherein the modulus defines measure of stiffness of the biomimeticscaffold with the void space. In illustrative embodiment, the scaffoldmay have a modulus of approximately between 150 MPa and 600 MPa, whereinthe modulus defines measure of stiffness of the biomimetic scaffoldwithout the void space, where the modulus is calculated using across-sectional area of only material comprising the composite scaffold.

According to embodiments, the composite scaffold disclosed hereinprovides greater support for a larger quantity of regenerated tissuethrough staggered degradation rates of the scaffold components. Morespecifically, the first and second support matrixes 5 and 15 of scaffold10 have different degradation rates. In one embodiment, the secondsupport matrix 15, e.g. the sponge, degrades 2 to 12 times faster thanthe first support structure 5 based on mass loss or molecular weightloss. For example, the sponge comprising the second support matrix mayhave a mass loss by 3 to 6 months following implementation whereas thetextile weave comprising first support matrix may have mass loss at 12months following implantation. Such difference in the rate ofdegradation enables the considerable tissue ingrowth facilitated by theinterior void of the scaffold 10 to continue to be supported by thetextile fabric for a longer period of time. As indicated, the parameterof material degradation may be measured via loss of mass or molecularweight loss. In one embodiment, the composite scaffold may have adegradation profile of greater than or equal to 50% strength retentionfor at least approximately four weeks after implantation and a mass lossof 100% mass loss between approximately six and twelve months afterimplantation.

According to embodiments, the composite scaffold disclosed herein mayhave features which enhance usability and better performance onceimplanted. In embodiments, the scaffold 10 may have ends that narrow andtransition into suture-like dimensions or are modified, e.g. stitched orknotted, to attach to conventional suture used in the proceduresdescribed herein. In embodiments, the support structure 5, e.g., thetextile, has ends or edges that are modified to be heat set orembroidered or impregnated with other materials to facilitate betterhandling, better integration with the existing tissue and to furtherreduce dimensional distortion of the scaffold 10 under pressure,tensile, or shear forces. In embodiments selected sections of thescaffold 10 may be repeated, either randomly or with fixed rapidity toincrease or decrease the density of the scaffold by increasing ordecreasing the density of the textile, for example, by a change in thetextile pattern of the first support structure 5. In embodiments, suchrepeat regions may be chosen to alter the surface finish of the scaffoldby altering the parameters of lyophilization, smoothness or roughness,of the exterior surface of the scaffold to enhance acceptance of thescaffold once implanted.

In embodiments, the spacer elements 18 may be located in only part ofthe interior space 16 of scaffold 10, e.g. a hollow lumen, asillustrated in FIG. 2D. In other embodiments, the spacer elements 18 mayhave any of a regular or irregular repeating placement pattern withinthe interior space 16 between the layers 12 and 14 of the scaffold 10.In other embodiments, the spacer elements 18 themselves may beimplemented with a textile, such as felt, or tissue or tissue derivedmaterials, or as otherwise described herein.

According to embodiments, the composite scaffold could also be seededwith cells for a temporary pre-culture period to allow the cells toelaborate a collagen-rich extracellular matrix on the sponge and textilecomponents. The scaffold could then optionally be decellularized toleave a matrix template having native extracellular matrix proteins onthe textile structure and the scaffold subsequently implanted to repaira tendon or ligament in vivo.

Scaffold Pore Characteristics

Multiple samples of composite scaffolds manufactured in accordance withexamples one and two and the processes described herein were tested todetermine various behavioral characteristics as described below. Themicroporous matrix in each sample composite scaffold has a multitude ofinterconnected pores opening to an exterior surface of the microporousmatrix and the composite scaffold. Various characteristics of the poreswithin the microporous matrix, and, accordingly, the composite scaffold,are measurable by Mercury Intrusion Porosimtery (MIP) or gas adsorption.Mercury is a non-wetting liquid that will not actively infill intoporous structures. However, by applying pressure, using MIP, mercury canbe forced into the pores of the microporous matrix, with higherpressures allowing the mercury to enter smaller pores. By accuratelymonitoring a volume of mercury while step-wise increasing the appliedpressure, pore size (diameter) and pore volume can be accuratelymeasured. The pore size and volume measurements can be used to determinemultiple properties of the microporous matrix and the composite scaffoldgenerally.

Surface Area

An important characteristic of the disclosed composite scaffolds is theratio of the scaffold surface area per unit weight of the scaffold. Thedisclosed composite scaffold, due to the extensive multitude ofinterconnected pores within the microporous matrix supported by the 3Dtextile support structure, has a large surface area onto which cellmigration and subsequent neo-tissue development may occur. The totalsurface area of the interconnected pores and the exterior of thecomposite scaffold is more accurately measurable using MIP, instead ofjust geometric dimensions and image quantification. Surface area may becalculated from the known diameter of the pores, measured via MIP, byassuming the pores are spheres using the following formula:A=4πr ²

As such, the surface area parameter represents an amount of surface areaof the composite scaffold per unit weight of the composite scaffoldarea, measurable in meters squared per gram (m²/g). FIG. 8 is a graph 80of test data showing the relationship of the cumulative total poresurface area relative to pore diameter, measured in micrometers, for anumber of composite scaffold samples as well as a sample comprising onlythe 3D textile comprising support structure 5. In the samples of FIG. 8,the 3D textile support structure 5, whether alone or populated with amicroporous matrix 15, comprised PLLA fibers. All samples were producedin accordance with the methods and Examples 1 and 2 described herein. Inembodiments, a disclosed composite scaffolds may have a surface area perweight unit which range from between approximately 0.3 m²/gram and 1.5m²/gram. The disclosed composite scaffolds may have a surface area perweight unit which range from between approximately 0.6 m²/gram and 1.2m²/gram. The disclosed composite scaffolds may have a surface area perweight unit, from between approximately 0.71 m²/gram and 1.0 m²/gram.

The total surface area of the interconnected pores and the exterior ofthe composite scaffold is also more accurately measurable using gasadsorption, instead of just geometric dimensions and imagequantification, such as with krypton gas. The Table below illustratestwo samples having a 5 mm width and a 40 mm length. The surface area ofthe composite scaffold is between approximately 0.3 m²/gram and 15m²/gram, as measured by krypton gas adsorption for pores having adiameter less than 1 μm.

Sample BET SA (m2/g) 5 mm 0.5826 5 mm 0.5558

Total Pore Volume

Another important characteristic of the composite scaffold is the highvolume of void space due, in part, to the number, size, orientation andinterconnectivity of the pores which collectively define void spacewithin the microporous matrix. Such high total pore volume facilitatesmore rapid blood absorption, cell migration and subsequent neo-tissuedevelopment. The total volume of pores collectively forming the voidspace within the microporous matrix may be measured directly using MIPby monitoring the change in Mercury volume during the MIP process. Assuch, the pore volume parameter of the composite scaffold represents atotal cumulative void volume per unit weight of the composite scaffold,e.g. cm³/g. FIG. 9 is a graph 90 showing the relationship of thecumulative total pore volume as measurable in centimeters cubed per gramrelative to pore diameter, as measured in micrometers for a number ofcomposite scaffold samples as well as only the textile only supportstructure. In the samples of FIG. 9, the textile support structure,whether alone or populated with a microporous matrix, comprises PLLAfibers. All samples were produced in accordance with the methodsdescribed herein. In embodiments, the disclosed composite scaffold mayhave a total pore volume which ranges from between approximately 3.0cm³/gram and 9.0 cm³/gram. The disclosed composite scaffolds may have avolume which ranges from between approximately 3.5 cm³/gram and 7.0cm³/gram. The disclosed composite scaffolds may have a total pore volumewhich ranges from between approximately 4.0 cm³/gram and 5.0 cm³/gram.

Porosity

Another important characteristic of the composite scaffold is porosity,that is the measurement of the void space volume within the microporousmatrix as a percentage of the measurable volume of the compositescaffold itself. Such calculation may be done using measurements takenduring MIP. During the MIP process, the mass of each sample is known, asis the occupied volume of the sample by monitoring mercury volume. Atthe lowest applied pressure during MIP, there should be no mercuryinfill into the scaffold, so bulk density of the composite scaffold canbe calculated. At the higher applied pressures during MIP, the compositescaffold should be near-complete mercury infill. Accordingly, thescaffold skeletal density can be calculated as follows:Porosity=100*1−(density at low pressure/density at high pressure)

In this manner, the measurable volume of the composite scaffold is notcalculated geometrically but through relative densities. FIG. 10 is agraph 100 of the relationship of the composite scaffold density in gramsper cubic centimeter in relation to Mercury pressure, as measured inpounds per square inch absolute, i.e. in a vacuum, measured inmicrometers, for a number of composite scaffold samples as well as onlythe textile only support structure. In the samples of FIG. 10, thetextile support structure, whether alone or populated with a microporousmatrix, comprises PLLA fibers. All samples were produced in accordancewith the methods described herein. In embodiments, the disclosedcomposite scaffold may have a porosity which ranges from betweenapproximately 75% to 98%. In embodiments, the disclosed compositescaffold may have a porosity which ranges from between approximately 80%to 90%. In embodiments, the disclosed composite scaffold may have aporosity which ranges from between approximately 80% to 85%.

Permeability

Another important characteristic of the composite scaffold is thepermeability of the microporous matrix which facilitates more rapidabsorption of fluids, particularly blood, both during and afterimplantation, to accelerate the process of cell migration and subsequentneo-tissue development. The microporous structure, e.g. collagen, insidethe textile support structure facilitates a more uniform andwell-defined pore structure compared to a collagen sponge alone, with apermeability of approximately 200% of the permeability of a collagensponge by itself. This is due, at least in part, to the more uniform andwell-defined structure of interconnected pores. Reproduciblepermeability values can be calculated from Mercury Intrusion Porosimetry(MIP) data using the Katz-Thompson equation set forth below:

$k = {\frac{1}{89}\left( D_{\max} \right)^{2}*\frac{D_{\max}}{D_{c}}*\varphi*{S\left( D_{\max} \right)}}$

-   -   Where:    -   k (mD): air permeability    -   Pt (psia): pressure at which Hg starts to flow through pores    -   D_(c) (μm): diameter corresponding to Pt (D_(c)=180/Pt)    -   D_(max) (μm): diameter at which hydraulic conductance is a        maximum    -   hydraulic conductance: measure of the ease that a fluid flows        through a porous material    -   φ: porosity from MIP data (subtract inaccessible void space in        fibers)    -   S(D_(max)): fraction of connected pore space that is size        D_(max) and larger/fraction of total porosity filled at D_(max)

An explanation of how to calculate permeability using the aboveKatz-Thompson equation is set forth in a publication by Goa and Hu,entitled estimating permeability using median poor—throat radiusobtained from Mercury intrusion precocity, J. Geophysics. Eng. (2013).In this manner, reproducible permeability values can be calculated fromdata collected during MIP. In embodiments, the disclosed compositescaffold may have a permeability which ranges from between approximately1200 and 3000 millidarcy. In embodiments, the disclosed compositescaffold may have a porosity which ranges from between approximatelyfrom between approximately 1400 and 2600 millidarcy. In embodiments, thedisclosed composite scaffold may have a porosity which ranges frombetween approximately from between approximately 1600 and 2000millidarcy.

Total Surface Area/Scaffold Volume

Another important characteristic of the composite scaffold is the ratioof the total surface area/scaffold volume. The surface area per givensample is determinable from MIP. The skeletal density can be calculatedas explained above with reference to the porosity parameter. Surfacearea is reported in units of square meters per sample weight unit (m²/g)and can be converted to meters cubed by multiplying by the sample mass.Scaffold volume is equal to the sample mass divided by the skeletaldensity. In embodiments, the disclosed composite scaffold may have avoid space surface area to scaffold volume between approximately 5,000cm²/cm³ and 16,000 cm²/cm³. In embodiments, the disclosed compositescaffold may have a void space surface area to scaffold volume betweenapproximately 7,000 cm²/cm³ and 14,000 cm²/cm³. In embodiments, thedisclosed composite scaffold may have a void space surface area toscaffold volume between approximately 9,000 cm²/cm³ and 12,000 cm²/cm³.

Pore Size

Another important characteristic of the composite scaffold is medianpore size of the interconnected pores within the void space of themicroporous matrix 15, as measured in micrometers. The pores with themicroporous matrix must be large enough to allow cell infiltration whilenot being so large that it slows cell proliferation and formation ofneo-tissue prior to reabsorption of the microporous matrix followingimplantation. In accordance with the disclosure, a number of pores of agiven diameter are effectively measured by tracking intrusion volume ata given pressure during MIP. From this, median pore size and pore sizedistribution are both reported. FIG. 12 is a graph 120 illustratinggraphically the relationship of the distribution of pore diameter, asmeasured in micrometers relative to the logarithmic differential volumeas measured in cubic centimeters per grams. In embodiments, themicroporous matrix may have a plurality of interconnected pores having amedian pore size of between approximately 10 μm to 70 μm. Inembodiments, the microporous matrix may have a plurality ofinterconnected pores having a median pore size of between approximately12 μm to 50 μm. In embodiments, the microporous matrix may have aplurality of interconnected pores having a median pore size of betweenapproximately 20 μm to 35 μm.

Another important characteristic of the composite scaffold isdistribution of pore sizes within the void space of the microporousmatrix of the composite scaffold, as measured in micrometers. Cumulativepore volume is determinable from MIP. The fractional contribution ofpores over a certain size to the void space can be calculated ascumulative void space at a given pore size divided by total void space.The distribution of pore sizes within the void space of the microporousmatrix is also illustrated in FIG. 12. As can be seen from FIG. 12, themajority of the collective void space within a microporous matrixcomprises pores having a size parameter greater than 10 μm. Inembodiments, the microporous matrix has a multitude of interconnectedpores collectively defining void space wherein at least approximately99% of the void space comprises pores having a size dimension of 10 μmor greater. In embodiments, the microporous matrix has a multitude ofinterconnected pores collectively defining void space wherein at leastapproximately 95% of the void space comprises pores having a sizedimension of 10 μm or greater. In embodiments, the microporous matrixhas a multitude of interconnected pores collectively defining void spacewherein at least approximately 80% of the void space comprises poreshaving a size dimension of 10 μm or greater.

Swelling and Absorbance

According to embodiments, the composite scaffold disclosed hereinprovides a measurably high absorptive capacity, e.g. capable ofabsorbing aqueous mediums, or wickability, to facilitate more rapid andgreater quantity of absorbed biologic fluids and/or cells within thescaffold. In particular, the absorbance capacity of the compositescaffold can be measured from the following formula:% Absorbance=(Sample wet mass−samples dry mass)/Sample dry mass*100

In embodiments, the disclosed composite scaffold has a measurable dryweight value representing a weight of the scaffold in a substantiallydry state and a measurable dry volume value representing a volume of thescaffold in a substantially dry state, with an increase of betweenapproximately 200% and 600% of the weight value of the scaffold fromfluid absorption changing the dry volume value of the scaffold betweenapproximately 0% and 10%. The percent volume change of the compositescaffold can be measured from the following formula:% Volume Change=(Sample wet volume−sample dry volume)/Sample dryvolume*100

According to embodiments, the composite scaffold disclosed hereinprovides a reduced swelling profile, e.g. resists dimensional changeswith increased absorption fluids. In particular, the percent swellingchange of the composite scaffold can be measured from the followingformula:% Swell=(Sample wet mass−samples dry mass)/(Sample wet mass)*100

In embodiments, the disclosed composite scaffold has a measurable dryweight value representing a weight of the composite scaffold in asubstantially dry state and a measurable dry length value representing adimensional parameter of the composite scaffold in a substantially drystate, with an increase of between approximately 200% and 600% of theweight value of the composite scaffold from fluid absorption changingthe dry length value of the composite scaffold by less than betweenapproximately 0% and 3%. The percent length change of the compositescaffold can be measured from the following formula:% Length Change=(Sample wet length−sample dry length)/Sample drylength*100

In embodiments, the disclosed composite scaffold a measurable dry weightvalue representing a weight of the composite scaffold in a substantiallydry state and a measurable cross sectional profile value representing adimensional parameter of the composite scaffold in a substantially drystate, with an increase of between approximately 200% and 600% of theweight value of the composite scaffold from fluid absorption changingthe cross sectional profile value of the composite scaffold by betweenapproximately 0% and 10%. The percent cross sectional profile change ofthe composite scaffold can be measured from the following formula:% Cross sectional profile change=((Sample wet width*sample wetheight)−(Sample dry width*sample dry height))/(Sample dry width*sampledry height)*100

Other relevant form are as followsulas:% Density Wet=((Sample wet weight/sample wet volume)/(sample dryweight/sample dry volume)*100% Thickness Change=(sample wet height−sample dry height)/sample dryheight*100% Weight Wet=sample wet weight/sample dry weight*100% of Sample Volume filled=(Sample wet mass−samples dry mass)/(Sample dryvolume)

Composite scaffold devices are weighed throughout the manufacturingprocess, capturing both the mass of the textile alone, the mass afterbeing coated with PEG 400, and the mass after adding collagen solutionand subsequent lyophilization. The mass of the collagen microporousmatrix in each device can be calculated as follows:mass_(Collagen)=mass_(Scaffold)−mass_(textile+PEG 400)The % dry weight of the collagen compared to the whole compositescaffold device can then be calculated:

$\%\mspace{14mu}{dry}\mspace{14mu}{weight}\mspace{14mu}{of}\mspace{14mu}{collagen}\mspace{14mu}{in}\mspace{14mu}{BioBrace}{= \frac{mass_{Collagen}}{mass_{Scaffold}}}$

Category Scaffold Density

Another important characteristic of the composite scaffold is scaffolddensity. According to embodiments, for the composite scaffold disclosedherein has a higher density or mass of the support matrix provides theprimary and bulk structure of the disclosed scaffold, in comparison tothe more porous matrix disposed therein. More specifically, the firstand second support matrixes 5 and 15 of scaffold 10 have differentdensities or mass components relative to each other. In one embodiment,the first support structure 5, e.g., the textile, has a measurable massor density which is greater than or equal to one times that of the massor density of the second support matrix 15, e.g. the sponge, and, morepreferably, between 2 to 5 times that of the mass or density of thesecond support matrix 15. In embodiments, the disclosed compositescaffold may have a maximum scaffold density of less than 0.5 g/cm³, andspecifically between approximately 0.05 g/cm³ and 0.3 g/cm³

Methods of Manufacture

Methods for manufacturing the composite scaffold in accordance with thedisclosure are as follows. A 5 mm wide, 3 mm tall, and 260 mm longcomposite scaffold for ACL repair or augmentation made from athree-dimensional PLLA textile filled with a highly porous collagenmatrix is manufactured, as follows. A three-dimensional (3D) textilewhich comprises the support structure is manufactured using the doublepillar pattern illustrated in FIG. 2A in accordance with the techniquethe warp knitting technique described. The resulting structure has topand bottom layers of 6 wales each. The corresponding wales top andbottom layers of the interconnected by a series of knitted spacing yarnsextending through the void space in the Z-direction, e.g. normal to theX-Y plane of the outer layers 12 and 14, and interconnecting the layers12 and 14. The 3D textile is received as a continuous length textile, 5mm wide and 3 mm tall and is ultrasonically scoured, e.g. washed, insolution of DI and IPA to remove particulate and yarn spin finish.Multiple washes, replacing solution in between washes, are used. Thetemperature of the wash solution may be room temperature, or up to 40 C.The 3D textile is then air dried, and cut to length.

An alternative method of preparing the 3-D textile prior to coating witha hydrophilic solution involves wrapping the continuous length textile,not overlapping, around a frame, also known as a tenter frame, or suturerack, with moderate tension. The wrapped frame is then submerged in adistilled water and isopropyl alcohol solution, and washed eitherultrasonically or in a shaker bath for agitation. Multiple washes,replacing solution between washes, may be used. The temperature of thewash solution may be room temperature, or up to 40 C. The 3D textile isthen air dried on the rack, under tension. The textile is then cut tolength, while under tension, on the rack, creating uniform lengths. Byutilizing the suture rack, washing under tension, and drying undertension, the textile is heat-set, reducing wrinkles, keeping top andbottom textile faces opposed, and tightening the knit structure,resulting in less elongation of the final textile under load.

The scoured and cut to length of 3D textile is then submerged in asolution of polyethylene glycol (PEG) and ethanol to increasehydrophilicity. The concentration of PEG in ethanol is specificallycontrolled to result in a controlled weight percentage of PEG on the 3Dtextile. The 3D textile is then air dried. An alternative method ofpreparing the 3-D textile prior to coating with a hydrophilic solutioninvolves submerging the 3D textile in the PEG and Ethanol solution,after scouring, but before cutting to length. An additional alternativemethod involves submerging the 3D textile as wrapped on the frame, afterscouring, but before cutting, in the PEG and ethanol solution. In theabove-mentioned steps, multiple combinations of each alternative may beutilized to achieve the same outcome.

Next, a 0.6% collagen solution by weight is made up using low molarityacetic acid and powder-form Type-1 bovine collagen is blended and vacuumprocessed to remove trapped air bubbles. A different low molarity acidsuch as hydrochloric acid may be used to make the collagen solution.Additionally, an alternative process may remove trapped air bubbles, forexample, by spinning the solution in a centrifuge.

Different weight percent collagen solutions can be used. Increasing theweight percentage of collagen increases the amount of collagen in thematrix. Decreasing the weight percentage of collagen reduces the amountof collagen in the matrix. These changes will affect the final collagenmatrix density, structural characteristics, and porosity when utilizedwith the lyophilization process described herein.

The stainless-steel mold 57 shown in FIG. 5B is used to guide infill ofcollagen solution into the 3D textile and through the next step,lyophilization, to create the collagen sponge matrix structure. Thecavities of the mold are filled with a small amount of collagensolution. Then, 3D textile lengths are placed into the mold, 3D textilefaces parallel to the bottom of the cavity, and clamps are used on eachend to secure the 3D textiles and to prevent movement. These clamps havean additive benefit, in the following step, Lyophilization, by creatingareas on each end that are flat without porous collagen matrix, used forproduct handling and suture attachment.

Then, additional collagen solution is filled into the cavities with thetextile, completely submerging the textile in collagen solution. Then,the mold with textile and collagen solution is vacuum processed toremove remaining air within the 3D textile to completely infill thetextile with solution. The mold, with textile and collagen solution, areplaced into a shelf lyophilizer, and the temperature brought down to −55C over a period of approximately 2 hrs. The textile, infilled with adry, highly porous and low-density collagen matrix, is removed from themold cavities and placed into a sealed chamber on a wire rack. Aformaldehyde and ethanol solution is poured into a tray, and the trayplaced under the rack of product, and the chamber door sealed. Vaporfrom the solution crosslinks the collagen within the textile. Afterapproximately 2 hours, the tray is removed, and the product moved intoan aeration chamber, in which clean, dry air is pumped through and outof the chamber, which effectively stops the crosslinking process. Aftera period of warming and vacuum, a highly porous, low density collagenmatrix is formed within the 3D textile.

A 23 mm wide, 3 mm tall, and 30 mm long composite scaffold for RotatorCuff repair or augmentation made from a three-dimensional PLLA textilefilled with a highly porous collagen matrix is manufactured, as follows.A 5 mm wide, 3 mm tall, and 260 mm long composite scaffold for ACLrepair or augmentation made from a three-dimensional PLLA textile filledwith a highly porous collagen matrix is manufactured, as describedhereafter. A three-dimensional (3D) textile which comprises the supportstructure is manufactured using the double pillar pattern illustrated inFIG. 2A in accordance with the technique the warp knitting techniquedescribed. The resulting structure has top and bottom layers ofapproximately 25 wales each. The corresponding wales top and bottomlayers of the interconnected by a series of knitted spacing yarnsextending through the void space in the Z direction and interconnectingthe layers.

The 3D textile is received as a continuous length textile, 5 mm wide and3 mm tall and is ultrasonically scoured, e.g. washed, in solution of DIand IPA to remove particulate and yarn spin finish. Multiple washes,replacing solution in between washes, are used. The temperature of thewash solution may be room temperature, or up to 40 C. The 3D textile isthen air dried, and cut to length. The scoured and cut to length of 3Dtextile is then submerged in a solution of PEG and ethanol to increasehydrophilicity. The concentration of PEG in ethanol is specificallycontrolled to result in a controlled weight percentage of PEG on the 3Dtextile. The 3D textile is then air dried.

Next, a 0.6% collagen solution by weight is made up using low molarityacetic acid and powder-form Type-1 bovine collagen is blended and vacuumprocessed to remove trapped air bubbles.

The stainless-steel mold shown in FIG. 5B is used to guide infill ofcollagen solution into the 3D textile and through the next step,Lyophilization, to create the collagen sponge matrix structure. Thecavities of the mold are filled with a small amount of collagensolution. Then, 3D textile lengths are placed into the mold, 3D textilefaces parallel to the bottom of the cavity, and clamps are used on eachend to secure the 3D textiles and to prevent movement. These clamps havean additive benefit, in the following step, Lyophilization, by creatingareas on each end that are flat without porous collagen matrix, used forproduct handling and suture attachment.

Then, additional collagen solution is filled into the cavities with thetextile, completely submerging the textile in collagen solution. Then,the mold with textile and collagen solution is vacuum processed toremove remaining air within the 3D textile to completely infill thetextile with solution. The mold, with textile and collagen solution, areplaced into a shelf lyophilizer, and the temperature brought down to −55C over a period of 2 hrs. A vacuum is pulled in the lyophilizer chamber,and the shelf temperature gradually increased, providing energy to thefrozen solvent, allowing the process of sublimation to occur. Thesublimated solvent is collected in a separate condenser and fullyremoved from the inflammation. After a period of warming and vacuum, ahighly porous, low density collagen matrix is formed within the 3Dtextile.

The mold design may be such that the whole scaffold becomes encapsulatedin the collagen gel this may have the benefit of shielding the body fromthe textile scaffold component with the more biocompatible collagen gel.

Medical Procedures

The composite scaffolds described herein may be utilized in a wide arrayof medical procedures including to reinforce a suture repair, standalone repair or reconstruction, or reconstruction using a tissue graftand for fixation purposes. Reinforcement of a repair or reconstructionusing the composite scaffold may be applicable to the knee, ankle,shoulder elbow and hand, and non-musculoskeletal soft tissue. The kneemay include any of ACL (anterior cruciate ligament), PCL (posteriorcruciate ligament), LCL (lateral collateral ligament), MCL (medicalcollateral ligament), MPFL (medial patellofemoral ligament), ALL(anterolateral ligament), and Posterolateral Corner Injury (fibularcollateral ligament, popliteus tendon, popliteofibular ligament). Theankle may include any of the ATFL (anterior talofibular ligament) andCFL (calcaneofibular ligament). The shoulder elbow and hand, may includeany of the rotor cuff (supraspinatus, infraspinatus, subscapularis, andteres minor tendons), acromioclavicular ligament, UCL (ulnar collateralligament), and flexor tendon. Non-musculoskeletal soft tissue mayinclude any of the breast, abdominal wall, and pelvic floor. Thecomposite scaffolds described herein may be utilized for fixation ofpermanent and re-absorbable materials, including sutures, sutureanchors, tacks, and staples.

The physical dimensions and biomechanical characteristics of thecomposite scaffolds disclosed herein are optimized for use in a widearray of medical procedures including to reinforce a suture repair,standalone repair or reconstruction, or reconstruction using a tissuegraft and for fixation purposes. Reinforcement of a repair orreconstruction using the composite scaffold may be applicable to theknee, ankle, shoulder elbow and hand, and non-musculoskeletal softtissue. Such physical characteristics are measurably different thanthose of commercially available products such as hernia mesh andorthopedic suture tape and are more suitable for the above describedprocedures. For example, orthopedic suture tape exists, and ismeasurable as a three-dimensional entity, for all intents and purposesrelative to surgery it is effectively two-dimensional with little valuefor regenerating the volume of tissue necessary to enhance or mimic thecharacteristics of tendons or ligaments. For surgical meshes and patchesconstructed of bioresorbable materials, which have broad applicationsand can be considered scaffolds, the resulting tissue plane that isformed following total resorption of the material can be quite thin andweak; this is due to a lack of thickness and/or sufficient void volumeof suitable pore size for cellular ingrowth within the scaffold.Therefore, there is a clear need to create tissue scaffolds ofsufficient thickness that regenerate thicker and stronger tissue planesfollowing polymeric degradation.

In an exemplary embodiment, FIG. 12 and Table 4 below illustrates, overthe number of samples, that a tendon augmented by the disclosedcomposite scaffold, is consistently stronger and capable of handlinggreater force over similar extension than the tendon alone.

TABLE 4 Sample 1 Sample 2 Sample 3 Sample 4 Augmented (N) 118.5 128 241182.5 Tendon Alone (N) 81.5 97.5 202 150 % Increase 31% 24% 16% 18%

Another alternative form of the disclosed composite scaffold isutilizing a tubular spacer, whether warp or weft knit, which can be usedas a “sheath” over autograft, allograft, or a repaired tendon orligament. One method of producing this is to take a flat spacer fabricand then attach the opposing edges, by sewing, heat sealing, or othermeans, to create a tube, as illustrated in FIG. 14. Alternatively, acustomized circular knitter can be used to knit a tubular spacer fabricwithout a connecting seam. Another alternative method of making atubular spacer is to weave the structure by method of 3D circular wovenpreform, method and structure is illustrated in FIG. 15.

An alternative method of manufacturing the textile component, as thestructure to hold the porous matrix, is to 3D print a structure from anelastic or non-elastic material, which will then be infilled with theporous matrix.

Alternatively, both the structure and the matrix can be 3D printed fromone or multiple materials, either as separate but combined entities, oras a single entity that provides both strength, porosity, and resistanceto compression.

In embodiments, the scaffold comprises a composite structure with atextile outer cover to provide strength and a 3D printed inner supportstructure to provide resistance to compression. Such scaffold may beeither rectangular or tubular is shape. Braiding may be used as a costeffective method of producing a tubular structure. By braiding over a 3Dprinted inner support structure insert the required contiguous space fortissue ingrowth is provided. Polymer fibers braided longitudinally intoan exterior braid structure may be provided to further modulate thetensile characteristics of the scaffold.

EXAMPLES Example 1—Manufacture of Textile Scaffold

A 75 denier 30 filament poly-L-Lactic Acid (PLLA) yarn was produced foruse in manufacture of scaffold fabrics. A warp beam was produced for usein a Karl Mayer Double Needle Bar Machine to produce the fabric. A 5 mmwide fabric of 6 wales across its width and a 23 mm wide fabric with 27wales across were produced, i.e. using a 22 gauge needle bed. The twosurface layers were separated in the Z direction by spacer yarns to makefabrics 2 mm thick. The fabric was scoured in an ultrasonic bath with amixture of deionized water and iso propyl alcohol and dried.

Example 2—Manufacture of ACL Augmentation/Repair Device

A 0.6% collagen solution (by weight) was made up using low molarityAcetic Acid and powder-form Type-1 bovine collagen. This solution wasblended and vacuum processed to remove trapped air bubbles. Astainless-steel mold, as shown in FIG. 5A, its cavities filled with asmall amount of collagen solution. The textile scaffold from Example 1,a 26 cm long and 5 mm wide sample, were placed into the mold, withtextile faces parallel to the bottom of the cavity, and clamps used oneach end to secure the textile and prevent movement. Additional collagensolution was filled into the cavities with the textile, completelysubmerging the textile in collagen solution. The mold with textile andcollagen solution was vacuum processed to remove remaining air withinthe textile to completely infill textile with solution.

The mold was then placed in an SP Scientific AdVantage Plus Lyophilizerand the samples lyophilized, the lyophilization process taking theinterior of the Lyophilizer from room temperature to −55 C over a periodof 2 hrs. The textile, infilled with a dry, highly porous andlow-density collagen matrix, was removed from the mold cavities andplaced into a sealed chamber on a wire rack. A formaldehyde and ethanolsolution was poured into a tray, and the tray placed under the rack ofproduct, and the chamber door sealed. Vapor from the solution crosslinksthe collagen within the textile. After 2 hours, the tray was removed,and the product moved into an aeration chamber, in which clean, dry airwas pumped through and out of the chamber, which effectively stops thecrosslinking process. The final device was suitable for use in ACLaugmentation or repair

Example 3—Manufacture of Rotator Cuff Augmentation/Repair Device

Following the methodology of Example 2 a mold suitable to accommodate a23 mm wide fabric was used to impregnate 50 mm by 23 mm pieces of fabricfrom Example 1, but instead using the mold of FIG. 5B. The final devicewas suitable for use in rotator cuff augmentation or repair

Example 4—Manufacture of Matrix Material

A 0.6% collagen solution (by weight) was made up using low molarityAcetic Acid and powder-form Type-1 bovine collagen. This solution wasblended and vacuum processed to remove trapped air bubbles. The solutionwas then lyophilized same as in Examples 2 and 3.

Example 5—Demonstration of Tendon Augmentation

-   -   A Porcine profundus tendon was obtained from a local abbatoir.        The composite scaffold device from Example 1 was doubled over        the tissue and whip-stitched at one end with #2 suture. A        tensile test machine was used to mimic the graft preparation        table. The whip-stitched end secured in upper grip jaws of        tensile tester. Pretension achieved by loading both ends of        composite scaffold to appropriate force and securing lower grip        jaws. The construct was cycled to 3.75 mm extension and back to        zero. The performance data are shown in Table 3 below, and        demonstrated the ability of the composite scaffold pre tension        to control the reinforcement provided by the scaffold.

TABLE 4 Stiffness Stiffness Stiffness Stiffness at 1 mm at 2 mm at 3 mmat 3.75 mm Force at Displace- Displace- Displace- Displace- 3.75 mm mentment ment ment (N) (N/mm) (N/mm) (N/mm) (N/mm) Tendon 222 30 75 108.3116.6 Alone Tendon 342 45.8 81.5 150 175 with BioBrace Tensioned to 14 NTendon 450 77.8 125 175 175 with BioBrace Tensioned to 20 N

While the size of the composite scaffolds described herein may varyaccording to the intended application, it is contemplated that ascaffold may have a lengths up to 1000 mm and a width from 3 mm to 1000mm to adopt to different soft-tissue sizes and applications. Further,the width may taper to suture width at the ends of the scaffold.

The present disclosure will be more completely understood through thefollowing description, which should be read in conjunction with thedrawings. In this description, like numbers refer to similar elementswithin various embodiments of the present disclosure. The skilledartisan will readily appreciate that the methods, apparatus and systemsdescribed herein are merely exemplary and that variations can be madewithout departing from the spirit and scope of the disclosure. The termscomprise, include, and/or plural forms of each are open ended andinclude the listed parts and can include additional parts that are notlisted. The term and/or is open ended and includes one or more of thelisted parts and combinations of the listed parts.

At various places in the present specification, values are disclosed ingroups or in ranges. It is specifically intended that the descriptioninclude each and every individual sub-combination of the members of suchgroups and ranges and any combination of the various endpoints of suchgroups or ranges. For example, an integer in the range of 0 to 40 isspecifically intended to individually disclose 0, 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40, and aninteger in the range of 1 to 20 is specifically intended to individuallydisclose 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, and 20. Real numbers are intended to be similarly inclusive,including values up to at least three decimal places.

The foregoing description has been presented for purposes ofillustration. It is not exhaustive and is not limited to the preciseforms or embodiments disclosed. Modifications and adaptations will beapparent to those skilled in the art from consideration of thespecification and practice of the disclosed embodiments.

As used herein, the indefinite articles “a” and “an” mean “one or more.”Similarly, the use of a plural term does not necessarily denote aplurality unless it is unambiguous in the given context. Words such as“and” or “or” mean “and/or” unless specifically directed otherwise.Further, since numerous modifications and variations will readily occurfrom studying the present disclosure, it is not desired to limit thedisclosure to the exact construction and operation illustrated anddescribed, and, accordingly, all suitable modifications and equivalentsfalling within the scope of the disclosure may be resorted to.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Any combination ofthe above embodiments is also envisioned and is within the scope of theappended claims. Moreover, while illustrative embodiments have beendescribed herein, the scope of any and all embodiments includeequivalent elements, modifications, omissions, combinations (e.g., ofaspects across various embodiments), adaptations and/or alterations aswould be appreciated by those skilled in the art based on the presentdisclosure. The limitations in the claims are to be interpreted broadlybased on the language employed in the claims and not limited to examplesdescribed in the present application. The examples are to be construedas non-exclusive. Furthermore, the steps of the disclosed methods may bemodified in any manner, including by reordering steps and/or insertingor deleting steps. It is intended, therefore, that the specification andexamples be considered as illustrative only, with a true scope andspirit being indicated by the following claims and their full scope ofequivalents.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Any combination ofthe above embodiments is also envisioned and is within the scope of theappended claims. Therefore, the above description should not beconstrued as limiting, but merely as exemplifications of particularembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended hereto.

What is claimed is:
 1. A scaffold structure comprising: first and secondouter layers having length dimensions defined by respective first andsecond ends thereof and defining an interior space therebetween, each ofthe first and second outer layers comprising a plurality ofinterconnected wales extending substantially parallel to the respectivelength dimensions; a plurality of spacer elements extendingsubstantially normal to the respective length dimensions through theinterior space and attached to each of the first and second outer layersproximate one of the plurality of wales, the plurality of spacerelements at least partially partitioning the interior space into aplurality of channels extending along the respective length dimensionsof the first and second outer layers, and a microporous matrix disposedwithin the interior space between the first and second outer layers. 2.The scaffold structure of claim 1 wherein each of first and second outerlayers have a corresponding number of wales and wherein the plurality ofspacer elements are attached to corresponding wales of each of the firstand second outer layers.
 3. The scaffold structure of claim 1 whereinthe plurality of spacer elements comprise spacer yarns.
 4. The scaffoldstructure of claim 1 wherein a distance between spacer elements along awale of the first or second outer layers is between approximately 100 μmand 2500 μm.
 5. The scaffold structure of claim 1 wherein a distancebetween wales in the first outer layer or the second outer layer isbetween approximately 200 μm and 5000 μm.
 6. The scaffold structure ofclaim 1 wherein the plurality of spacer elements have a length extendingbetween the first and second outer layers between approximately 100 μmand 5000 μm.
 7. The scaffold structure of claim 1 wherein the wales ofone of the first and second outer layers comprise a pillar stitch and anaxial lay-in yarn.
 8. The scaffold structure of claim 1 wherein thescaffold has an elongation at tensile failure of between approximately20% and 125%.
 9. The scaffold structure of claim 1 wherein the scaffoldhas an elongation at yield of between approximately 5% and 50%.
 10. Thescaffold structure of claim 1 wherein the scaffold has a stiffness ofapproximately between 2.5 N/mm and 25 N/mm.
 11. The scaffold structureof claim 1 wherein the scaffold has an ultimate strain of approximatelybetween 20% and 70%.
 12. The scaffold structure of claim 1 wherein thescaffold has an ultimate stress of approximately between 2.5 MPa and 30MPa.
 13. The scaffold structure of claim 1 wherein the scaffold has ayield stress of approximately between 2.5 MPa and 30 MPa.
 14. Thescaffold structure of claim 1 wherein the scaffold has a modulus ofapproximately between 2.5 MPa and 70 MPa, wherein modulus defines stressdivided by strain of a cross-sectional area of the scaffold, includingthe void space.
 15. The scaffold structure of claim 1 wherein thescaffold has a modulus of approximately between 150 MPa and 600 MPa,wherein modulus defines stress divided by strain of bulk material fromwhich the scaffold is comprised, excluding the void space.
 16. Thescaffold structure of claim 1 wherein the scaffold have a stiffness ofapproximately between 2.5 N/mm and 250 N/mm.
 17. The scaffold structureof claim 1 wherein the scaffold has a tenacity between approximately0.07 grams-force/denier and 1.10 grams-force/denier.
 18. The scaffoldstructure of claim 1 wherein the scaffold has a tenacity at failure ofapproximately between 0.3 grams-force/denier and 2 grams-force/denier.19. The scaffold structure of claim 1 wherein at least part of thescaffold is coated with a hydrophilic solution.
 20. The scaffoldstructure of claim 19 wherein the hydrophilic solution comprisesPolyethylene glycol (PEG).
 21. The scaffold structure of claim 1 whereinthe scaffold comprises monofilament, multifilament, or textured yarns,or any combination thereof, knitted into a three-dimensional structure.22. The scaffold structure of claim 1 wherein the scaffold comprises anycombination of bioresorbable polymers, natural polymers and/oradditives.
 23. The scaffold structure of claim 22 wherein the scaffoldcomprises any of homopolymers, copolymers, or polymer blends of any ofthe following: polylactic acid, polyglycolic acid, polycaprolactone,polydioxanone, polyhydroxyalkanoates, polyanhydrides, poly(orthoesters), polyphosphazenes, poly (amino acids), polyalkylcyanoacrylates,poly(propylene fumarate, trimethylene carbonate, poly(glycerolsebacate), poly(glyconate), poly(ethylene glycol), poly(vinyl alcohol)and polyurethane, or any combination thereof.
 24. The scaffold structureof claim 1 wherein the composite scaffold have a cross sectional area ofapproximately between 3 mm² and 3000 mm² wherein the cross sectionalarea defines an area of a two-dimensional shape of the scaffold at apoint perpendicular to the length of the scaffold, and wherein thecross-sectional area changes less than approximately 10% at a elongationpercentage of 5%.
 25. The scaffold structure of claim 1 wherein themicroporous matrix defines a multitude of interconnected porescollectively opening to an exterior surface of the microporous matrix.